LIQUID CHROMATOGRAPHIC DATA PROCESSING APPARATUS
20230384273 · 2023-11-30
Inventors
Cpc classification
G01N30/8675
PHYSICS
International classification
Abstract
Disclosed is a liquid chromatographic data processing apparatus capable of easily setting appropriate analytical conditions while taking sensitivity performance into account. The liquid chromatographic data processing apparatus includes a data processing unit that generates display data for performing a display in accordance with correspondence relationships of diameters of particles of a column filler that is data concerning an analytical condition of a chromatography apparatus and analytical characteristics that is data concerning separation performance, and a sensitivity performance index.
Claims
1. A liquid chromatographic data processing apparatus comprising a data processing unit that generates: display data displaying in accordance with a correspondence relationship of analytical condition data and analytical characteristic data of a chromatographic apparatus, wherein the analytical condition data is of diameters of particles of a column filler, and the analytical characteristic data are of a separation performance index and a sensitivity performance index.
2. The liquid chromatographic data processing apparatus of claim 1, wherein the display data are display data displaying values determined in accordance with graphs, tables, or given data.
3. The liquid chromatographic data processing apparatus of claim 1, wherein the data processing unit further generates display data displaying a diameter of particles at which the sensitivity performance index becomes optimal for a given separation performance index.
4. The liquid chromatographic data processing apparatus of claim 1, wherein the data processing unit further generates display data for displaying a correspondence relationship among a column length, a separation performance index, and a sensitivity performance index.
5. The liquid chromatographic data processing apparatus of claim 4, wherein the data processing unit further generates display data displaying the column length at which the sensitivity performance index or the separation performance index becomes optimal for a given separation performance index or a given sensitivity performance index.
6. The liquid chromatographic data processing apparatus of claim 1, wherein the data processing unit further generates display data for displaying a correspondence relationship among a flow rate of a mobile phase that is sent to a column, a high-speed performance index, and a pressure-related index.
7. The liquid chromatographic data processing apparatus of claim 6, wherein the data processing unit further generates display data in accordance with a correspondence relationship between the high-speed performance index and either the sensitivity performance index or the flow rate for the given pressure-related index.
8. A liquid chromatographic data processing apparatus comprising a data processing unit that generates display data for displaying a correspondence relationship between data concerning analytical conditions of a chromatographic apparatus and data concerning analytical characteristics, wherein the data concerning the analytical conditions is of a particle size of a column filler, and the data concerning the analytical characteristics is of a separation performance index.
9. A liquid chromatographic data processing apparatus comprising a data processing unit that generates display data for displaying a correspondence relationship between data concerning analytical conditions of a chromatographic apparatus and data concerning analytical characteristics, wherein the data concerning the analytical conditions is of a particle size of a column filler, and the data concerning the analytical characteristics is of a sensitivity performance index.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0045] First, an overview of the premise will be given.
[0046] First of all, it is necessary to describe in advance what sensitivity performance is.
[0047] The term “good sensitivity” refers to a characteristic in which a detection limit or a quantitative limit is low, and in the present invention, a detection limit with a smaller-the-better characteristic is adopted as an indicator of sensitivity performance. For the sake of simplicity, in the present invention, it is assumed that an absorbance detector is used, and the detection limit of HPLC is generally expressed as the concentration of an injected sample. A method that can measure a lower concentration of a sample is regarded as an analytical method with better sensitivity performance.
[0048] In the HPLC method, an SN ratio is used to calculate the detection limit. For example, it is assumed that SN ratio 200 is obtained by injecting 1 μL, of an analyte at a concentration of 100 nmol/μL and dividing a detection signal SSN corresponding to the peak height on the chromatogram by baseline noise NSN. When the detection limit is defined with SN ratio=2,1.00 nmol/μL, which is 1/100 times the original sample concentration, is calculated as the detection limit. In addition, when a margin is given and SN ratio=3 is adopted to define the detection limit, the detection limit deteriorates slightly to 1.50 nmol/μL, which is 3/200 times. In any case, the higher the peak height, the larger the detection signal SSN, and thus the larger the SN ratio. Here, the noise NSN is considered to be not dependent on the sample but is assumed to be fixed.
[0049] Therefore, in order to lower the detection limit, it is preferable that the concentration of the analyte in the flow cell of the detector is higher. This means that, when a certain amount of analyte is injected, it is preferable that the sample is passed through the column in a state in which the concentration distribution of the analyte in the sample volume is pulsed so as not to broaden the peak as much as possible.
[0050] Here, it is modeled that each peak on the chromatogram shows the shape of a normal distribution function. Let the standard deviation of this normal distribution function be σV (μL). σV is the peak volume characterizing the spread of the peak of the analyte in the mobile phase and is proportional to the peak width. In the case of isocratic elution, the number of theoretical plates N is expressed as Equation 6.
[0051] Here, VR (μL) is the retention volume. Since σV.sup.2 is a statistical variance and represents the spatial spread of the peak, σV.sup.2 is called the peak volume variance. A state in which the concentration of an analyte in the flow cell is high, means that when a certain amount of substance is injected, σV is small. Therefore, the smaller the σV, the larger the SSN corresponding to the peak height, and the lower the detection limit of the SN ratio method.
[0052] Equation 7 can be derived from the peak volume variance σV.sup.2.
[0053] Here, F (m.sup.3/s) is flow rate, ε is column porosity, S (m.sup.2) is column cross-sectional area, and Equation 7 is obtained because the flow rate F (m.sup.3/s) has the relationships of Equations 8 to 10.
V.sub.R=t.sub.RF [Equation 8]
F=εSu.sub.0 [Equation 9]
L=u.sub.0t.sub.0 [Equation 10]
[0054] Referring to the configuration of σV.sup.2 of Equation 7, excluding those that can be regarded as constants, Σ (m.sup.2) is defined to factor out performance-related parameters of chromatography (Equation 11).
[0055] Σ is called the height-length product because it is expressed as the product of the height equivalent to a theoretical plate H (m) and the column length L. Using Σ, σV.sup.2 of Equation 7 can be expressed as Equation 12.
σ.sub.V.sup.2=ε.sup.2(k+1).sup.2S.sup.2Σ [Equation 12]
[0056] Since the peak volume variance σV.sup.2 is preferably small in terms of lowering the detection limit, the high-length product Σ has the smaller-the-better characteristic. First, what Equation 12 represents will be described. The σV.sup.2 having the smaller-the-better characteristic is proportional to the column cross-sectional area S. In other words, it is desirable to reduce the inner diameter (diameter) of the column from 4.6 mm to 2 mm, and even to 1 mm. Reducing S significantly increases the concentration in the flow cell, thereby contributing to lowering the detection limit. Semi-micron LC exhibits a more advantageous effect on the detection limit than the so-called conventional LC.
[0057] In Equation 12, the porosity c and the retention coefficient-related (k+1) factor are multiplied, but these can be considered as constants. When the filler particles in the column are almost spherical, the porosity c is usually about 0.5, and the mobile phase fills the voids. When the mobile phase, the stationary phase, and the analyte are common, the retention coefficient k is constant. Even when the diameter of particles d.sub.P (μm) of the filler changes, it is considered that and k are constant.
[0058] Reducing the peak volume variance σV.sup.2 corresponds to reducing S in the radial direction of the column and to reducing Σ in the axial direction of the column. As the name implies, the height-length product Σ is the product of the height H and the length, so it is wise. However, a really brilliant idea for the computation is that Σ is defined as a variable obtained by multiplying the height equivalent to a theoretical plate H, which is a performance index in the axial direction, by the column length L (Equation 11).
[0059] The reduction of S means the reduction of the inner diameter of the column. Although not covered in the middle of discussion, the inner diameter may be independently changed before and after a certain discussion. Therefore, theoretically, S may be taken as a constant. In practice, when the inner diameter of the column is less than 1 mm, it is necessary to separately discuss the inner diameter of the column because the influence of the expansion outside the column and the inner wall of the column is not negligible. The present invention deals with sensitivity performance while focusing only on the smaller-the-better characteristic.
Aspect of Height-Length Product Σ
[0060] First, for the sake of simplicity, d.sub.P is fixed to 2 μm and operation input variables u.sub.0 and L are moved to recognize what kind of characteristic the variable Σ indicates.
[0061] Since Σ is the product of H and L, as illustrated in
[0062] The reasons for adopting the Opt. method will be described below. As described above, in terms of minimizing the detection limit, σV.sup.2 has the smaller-the-better characteristic like Σ has the smaller-the-better characteristic. As expressed by Equation 11, since N is multiplied by the square of H, when the separation performance N is requested as an input as described later, the linear velocity is set to the optimum linear velocity u.sub.opt to minimize the value of Σ, and desirably the minimum height equivalent to a theoretical plate H.sub.min is obtained. Alternatively, in other words, in the case of u.sub.opt, L becomes the minimum to obtain N as the input. When the linear velocity is increased to excess the optimum linear velocity u.sub.opt, since H increases, L must be extended to obtain a constant N. Even in the case where the linear velocity is below u.sub.opt, L must be extended. Therefore, in the case of minimizing the detection limit, H.sub.min needs to be obtained by setting the linear velocity to u.sub.opt. This is the reason for specifying u.sub.opt, i.e., adopting the Opt. method.
Visualization for Analytical Condition Search
[0063] Next, considering the characteristics of Σ in the base plane (u.sub.0, L) (see
[0064] An exemplary three-dimensional graph in the present invention: [0065] x-axis . . . separation performance index: number of theoretical plates N (larger-the-better characteristic) [0066] y-axis . . . diameter of particles d.sub.P of a column filler [0067] z-axis . . . sensitivity performance index: height-length product Σ (smaller-the-better characteristic)
[0068] When x and y are inputted, the column length L is determined unequivocally in the background. Since the Opt. method is adopted, when d.sub.P is specified first, the linear velocity is determined unequivocally to be the u.sub.opt corresponding to the d.sub.P, and H.sub.minis determined in conjunction. Next, since the input N is specified, L is essentially determined on the basis of the H.sub.min.
[0069] As can be seen from
[0070] A liquid chromatographic data processing apparatus that displays a three-dimensional graph in which the z-axis represents Σ.sub.opt as in
[0071] Here, for the diameter of particles d.sub.P, the lower limit is the smallest available diameter of particles d.sub.Pmin. Although Σ.sub.opt decreases monotonically with respect to d.sub.P, in some cases it may become a boundary condition in which the upper limit of pressure loss ΔP.sub.max is reached first. Accordingly, the diameters of particles d.sub.P at which the sensitivity performance index Σ.sub.opt is the best is found to be the smallest of the available diameters of particles d.sub.P where the lower limit diameter of particles d.sub.Pmin is present when the pressure loss is below the upper limit ΔP.sub.max. Note that the pressure loss may also be visualized so that the pressure loss can be easily monitored during condition searching.
[0072] The degree of influence of d.sub.P, which is an operational input variable, can also be read from
[0073] In addition, apart from the method of improving the sensitivity performance, in the case where N is increased with d.sub.P fixed, Σ.sub.opt also deteriorates in proportion to N. On the other hand, the d.sub.P is variable, the situation changes. For example, focusing on the contour line where Σ.sub.opt on the z-axis is constant at 2×10.sup.−6 m.sup.2 in
Relationship Between Σ and Diameter of Particles
[0074] A set of physical quantities related to the Opt. method can be obtained from the van Deemter's equation (Equation 3) dealing with the diameter of particles d.sub.P. The u.sub.opt (Equation 13) is derived from the first-order differential coefficient of u.sub.0 using Equation 3, and the minimum value H.sub.min is expressed by Equation 14. L and Σ3 that can be obtained by the u.sub.opt method become L.sub.opt (Equation 15) and Σ opt (Equation 16), respectively.
[0075] According to Equation 16, since the coefficients a, b, and c of the van Deemter's equation are common to each diameter of particles, Σ.sub.opt is only proportional to the square of N and the diameter of particles d.sub.P. In other words, when the diameter of particles becomes ½ times, i.e., changes from 4 μm to 2 μm, Σ.sub.opt improves by ¼ times. For example, when looking at the right-hand side cutout of N=30,000 plates, Σ.sub.opt is increased by a factor of ¼ from 4.63×10.sup.−6 (m 2) to 1.16×10.sup.−6 (m.sup.2). In addition, when looking at d.sub.P=5 μm on the rear wall side, Σ.sub.opt at N=15,000 plates is 3.61×10.sup.−6 (m.sup.2), whereas Σ.sub.opt at N=30,000 plates is 7.23×10 .sup.−6 (m.sup.2), and it can be seen that the detection limit is deteriorated by a factor of two.
[0076] ΔP, Π, and t.sub.0 related to the Opt. method will be expressed as ΔP.sub.opt (Equation 17), Π.sub.opt (Equation 18), and t.sub.opt(Equation 19), respectively.
[0077] Since the t.sub.opt and Σ.sub.opt obtained by the u.sub.opt method are each proportional to the square of d.sub.P, it is interesting that Σ.sub.opt has a simple proportional relationship with the holdup time t.sub.opt. In other words, when a predetermined separation performance level can be obtained without taking much time, the sensitivity performance is also improved.
[0078] The coefficients and the like used here are as shown in Table 1. These values may be provided in advance, for example, by the apparatus manufacturer or the like, or may be determined by user experiments or the like.
TABLE-US-00001 TABLE 1 list of coefficients related to calculation a (μm) b (×10.sup.−9 m.sup.2/s) c (×10.sup.−15 s/m.sup.2) ϕ.sub.P η (mPa .Math. s) 18 3.97 0.11 1,500 0.54
[0079]
[0080] In order to solve the problem, the minimum value of Σ.sub.opt is obtained on the basis of H.sub.min of the u.sub.opt method, but the input conditions are found from the base plane using the three-dimensional graph with the z-axis of Σ.sub.opt (
[0081] A method of optimizing the column length L.sub.opt will be exemplified using
[0082] On the basis of these relationships, it is possible to construct a liquid chromatographic data processing apparatus that displays the column length L.sub.opt at which the sensitivity performance index or the separation performance index as an evaluation index is the best, depending on, for example, the minimum available diameter of particles and the upper limit of the pressure loss, when the separation performance index N or the sensitivity performance index Σ.sub.opt is input.
[0083] For example, the problem of minimizing the detection limit under the requested condition of securing N=20,000 plates may be considered. In the case of using a filler with a d.sub.P of 2 μm, Σ.sub.opt=0.77×10.sup.−6 (m.sup.2) is obtained. In this case, since L.sub.opt=124 mm, it is desirable to have a column with a length of 125 mm. However, since an available column has a length of 150 mm, a re-computation is required. For 150 mm, Equation 15 yields Σ=0.93×10.sup.6 (m.sup.2) and N=24,000. For reference, for L.sub.opt=100 mm, the results, Σ.sub.opt=0.62×10.sup.−6 (m.sup.2) and N=16,000, are obtained. In this case, the requested condition of N=20,000 plates is not satisfied. Eventually, a 150-mm column with a filler diameter of particles of 2 μm will be chosen to minimize the detection limit. At the same time, t.sub.opt=49 (s) and ΔP.sub.opt=93 (MPa) are obtained (Table 2).
TABLE-US-00002 list of calculation results related to problems L.sub.opt (mm) 100 125 150 d.sub.P (μm) 2 2 2 u.sub.opt (mm/s) 3.0 3.0 3.0 H.sub.min (μm) 6.2 6.2 6.2 N 16,000 20,000 24,000 Σ.sub.opt (×10.sup.−6 m.sup.2) 0.62 0.77 0.93 t.sub.opt (s) 33 41 49 ΔP.sub.opt (MPa) 62 77 93
Add-On Speed-Up Method
[0084] There is a good practical optimization method for accelerating the optimization after finding high sensitivity performance conditions by using H.sub.min This is called the add-on speed-up method. Although high sensitivity performance is exemplified here, high separation performance can also be sped up as well. As described above, the minimum solution of Σ.sub.opt is determined on the basis of H.sub.min, but u.sub.0 exceeding u.sub.opt can be considered. In this case, the operational conditions d.sub.P and L at which Σ.sub.opt have been obtained are fixed.
[0085] Especially when a filler with diameter of particles of 2 μm or less is used, it is known that H does not deteriorate and almost maintains at H.sub.min even with increasing u.sub.0. This is because the term of the coefficient c in the van Deemter equation is proportional to the square of d.sub.P (Equation 3). The add-on speed-up method is based on the property that H is almost approximate to H.sub.min even with increasing u.sub.0. First, with Σ.sub.opt as the starting point, when u.sub.0 is increased, t.sub.0 is inversely proportional to u.sub.0 regardless of separation performance and sensitivity performance, and ΔP is proportional to u.sub.0 (
[0086] The add-on speed-up method is like a method of capturing two birds with one stone. That is, by further increasing the flow velocity after optimizing the sensitivity performance through the Opt. method, high-speed performance corresponding to the upper pressure limit is obtained while considering the degree of deterioration in sensitivity. The liquid chromatographic data processing apparatus plots u.sub.0, which is proportional to the flow velocity, on the horizontal axis, and displays sensitivity performance Σ, high-speed performance t.sub.0 related to high speed, and pressure loss ΔP on the vertical axis (
[0087] As can be seen from
Application of Add-on Speed-up Method to Separation Performance
[0088] The speed-up method has been discussed in terms of sensitivity performance above, but the viewpoint will be switched to separation performance. As can be seen from
[0089] Here, instead of Σ, the add-on speed-up method can also be applied to N (
Investigation of Σ-Related Matters Triggered by Fluorescence Detection Method
[0090] For an ultraviolet visible absorbance light intensity detector, technical matters related to Σ will be described from the perspective of a fluorescence detector. Here, it is assumed that a sample with an appropriate concentration is injected in a certain amount. Improving the sensitivity performance of a system under such simple conditions in which the sample is not concentrated and the injection volume is not doubled, simply means increasing an SN ratio.
Probability Density Function with Time Axis
[0091] When a substance is injected in an amount of n [mol], a Gaussian-like peak characterized by the standard deviation σ.sub.t[s] appears on the chromatogram on the time axis. This is called the probability density function. Since the area corresponds to n and is constant, when the peak is broad, the peak is linked to σ.sub.t and thus becomes lower. When the noise is assumed to be constant for simplicity, the high sensitivity performance means that the detection signal or peak is high, and the peak width σ.sub.t is narrow. Equation 20 represents a theoretical stage number N obtained from the standard deviation σ.sub.t of time, and is the same as Equation 6.
[0092] Here, t.sub.R is retention time.
[0093] In Equations 6 and 7, it is represented as σ.sub.v but can be associated with familiar time-axis chromatograms. The volume is the product of the displacement of the solute in the z-axis flow direction and the cross-section of the column perpendicular thereto. This plane is characterized by an effective cross-sectional area of the inner diameter of the column. Accordingly, taking into account only the flow direction, the z-axis displacement of the non-retaining component is equivalent to the time of the chromatogram of the non-retaining component when the linear velocity u.sub.0 is a proportional coefficient. This expression means that the column length L is equivalent to the hold-up time t.sub.0 via u.sub.0. Thus, the equivalence of time and z-axis displacement was ensured.
[0094] Here, σ.sub.z is the standard deviation in the z-axis flow direction
[0095] Referring to Equation 21 derived from Equations 7 and 20, it can be interpreted that the porosity ε is obtained by subtracting an effective column cross-sectional area from the column cross-sectional area S. In Equation 7, the factor (k+1) constituted by the retention coefficient increases the hold-up time t.sub.0 up to the retention time t.sub.R, while in Equation 21, σ.sub.t is directly obtained from the retention time t.sub.R and the theoretical stage number N. That is, it is found that the spatially expressed σ.sub.v [m.sup.3] can be converted to σ.sub.t [s] via u.sub.0 by dividing by the effective column cross-sectional area εS.
High-Length Product Σ.SUB.t .Expressed in Units of Time
[0096] In chromatograms, it can be understood that the z-axis displacement in the flow direction is represented by the time axis. On the other hand, the information derived from the column cross-sectional area appears on the vertical axis as described later. The chromatogram of the time axis has the advantage that only the z-axis displacement can be extracted as the horizontal axis coordinate.
[0097] Can the argument [m.sup.2] be expressed only in units of time? Since Σ is NH.sup.2, it can be defined that the square of the height H [m] of the plate is stacked by N sheets. The conversion of H into units of time using u.sub.0 produces the plate time t.sub.P. Accordingly, the height-length product Σ.sub.t[s.sup.2] in units of time is defined by Equation 22.
[0098] In addition, the squares of Σ and Σ.sub.t used in the coordinate transformations of three-dimensional graphs described later are defined as Ξ [m.sup.4] and Ξ.sub.t[s.sup.4], respectively (Equations 23 and 24).
Ξ≡Σ.sup.2 [Equation 23]
Ξ≡Σ.sub.t.sup.2 [Equation 24]
Absorbance Spectrophotometric Detection Method
[0099] By using chromatograms on the time axis, the peak area of the probability density function is proportional to the amount of substance. In other words, a chromatogram is considered to be a change in the amount of substance per time along the horizontal axis of time. Under a condition in which the linear velocity u.sub.0 is constant, even though the inner diameter of the column is reduced or increased, the peak shape of the chromatogram is exactly the same, as long as the phenomenon is captured over time. The reason is that the probability density function of the amount of a substance does not change with time on the horizontal axis when the column inner diameter increased or decreased.
[0100] However, the absorbance spectrophotometric detection method has the effect of semi-micro LC as mentioned above. This is because S in Equation 7 is reduced, and corresponds to the fact that the sample is not excessively diluted by the mobile phase. This is because the absorbance spectrophotometric detection method detects the concentration of the solute rather than the amount of substance. To avoid diluting the sample, it is advisable to minimize the inner diameter of the column and to reduce the flow rate. When the diffusion caused by the flow cell is taken into consideration, the cell volume should be reduced as the column is made thinner.
[0101] On the other hand, according to Lambert-Behr's law, the longer the optical path length of the cell, the more the detection signal can be increased. In the case of the absorbance spectrophotometric detection method, it is desirable to have a small cell volume while maintaining a long optical path length. In reality, this would involve a comprehensive design around the cell so as not to increase the detection noise.
Fluorescence Detection Method
[0102] Fluorescence detectors are ideally regarded as a method of directly detecting the amount of substance, and the action of Σ contributes to high sensitivity. In addition, to increase the detection signal, it is preferable that the volume of the flow cell is simply increased to detect a large amount of substance. The volume increase is excessive, diffusion occurs in the flow cell. For example, it is necessary to design the cell volume to be less than 1/100 of the mobile phase volume that forms the peak.
[0103] Since the fluorescence detection method does not detect the concentration, and the amount of substance per unit time does not change as described about the aforementioned time-axis chromatogram, the effect of semi-micro LC conversion cannot be expected. However, it is conceivable to reduce to reduce the mobile phase volume for peak formation, relative to the cell volume at a level that peak broadening does not occur. This is simply a relative inversion of the relationship between the cell volume increase and the mobile phase volume. Even in the case of the fluorescence detection method, when the cell volume is set to a certain condition, since it is desirable that the concentration of the solute in the cell is higher, it is better not to dilute the sample. That is, there is an advantage of semi-micro LC in which the inner diameter of the column is reduced to reduce the flow rate. Since it is not intended to secure the optical path length, the cell shape is arbitrary. Both the absorbance and fluorescence detection methods have the advantage of not diluting although the reasons therefor differ.
Three-Dimensional Graph with Varying Diameter of Particles
[0104] When commercial columns are purchased, d.sub.P and L are discrete. However, when designing fillers and columns, d.sub.P and L need to be optimized to be continuous, that is, with real variables. In Patent Literature 3, a three-variable function N(ΔP, t.sub.0, d.sub.P) is disclosed. When three variables are used as inputs, since another axis is needed for the output N, the graph becomes four-dimensional. However, the four-dimensional graph cannot be illustrated. Three-dimensional graphs such as N(ΔP, t.sub.0) where d.sub.P is fixed is disclosed in Patent Literature 1. In the case of three-dimensional graphs, there are two types: N(t.sub.0, d.sub.P) with ΔP fixed; and N(ΔP, d.sub.P) with t.sub.0 fixed. Showing the three-variable function N(ΔP, t.sub.0, d.sub.P) as multiple three-dimensional graphs is useful for giving the user an image. In addition, the three-dimensional graphs may be sent frame by frame so as to be displayed as a moving picture. In any case, with the use of such an image, it is possible to understand the characteristics of the four-dimensional graph.
[0105] When the linear velocity for a certain d.sub.P is u.sub.opt, it is possible to obtain the maximum N compared to other diameters of particles. However, for example, when looking at the back wall of t.sub.0=150 sec at 60 MPa that is fixed in the graph as illustrated in
[0106] On the other hand, in
[0107] It has been found that even with the graphs with three variables such as N(ΔP, t.sub.0, d.sub.P), the situation can be grasped by fixing one variable. The liquid chromatographic data processing apparatus can display the N(t.sub.0, d.sub.P) graph as in
Normalized Pressure
[0108] The pressure loss ΔP (MPa) was affected by the viscosity η (Pa.Math.s) of the mobile phase as expressed by Equation 4, and there was a problem that performance indices related to the driving ability of the HPLC system and the pressure of the analysis method cannot be compared and evaluated correctly. To solve this problem, the normalized pressure p.sub.η(s−1), which is normalized by viscosity, is defined using Equation 25.
[0109] The viscosity η of pure water is 1 mPa.Math.s at 20° C. When ΔP is 100 MPa in the case of using 20° C. pure water as a mobile phase, p.sub.η becomes 10.sup.11s.sup.−1. When the mobile phase is a 60% aqueous acetonitrile solution, the viscosity is as low as η=0.54 mPa.Math.s, making it difficult to apply low pressure. Thus, even at the same ΔP of 100 MPa, p.sub.η becomes 1.85×10.sup.11s.sup.−1. It can be seen from Equation 25 that the strength of the driving ability acting on the HPLC, that is, the degree of influence on the velocity-length product Π can be more appropriately quantified by using the normalized pressure rather than simply using the pressure index. By using not only an HPLC system to which 100 MPa can be applied but also an analysis method involving p.sub.η of 10.sup.11s.sup.−1 which as has the larger-the-better characteristic, a purely comparative evaluation of high-speed and high-separation performance can be performed. The significance of defining p.sub.η will be described later.
[0110] By introducing the concept of p.sub.η, it is possible to universally express ΔP which may vary with the viscosity of the mobile phase depending on the analytical method. For example, it is better to understand p.sub.ηby converting ΔP (MPa) at each viscosity to ΔP (MPa) at η=1 mPa.Math.s. In other words, 100 MPa at 0.54 mPa.Math.s described above is equivalent to 185 MPa as the normalized pressure p.sub.η. Rather than a simple expression that the actual ΔP is 100 MPa, the expression that it is an analysis method equivalent to 185 MPa as the normalized pressure p.sub.η when taking into account the viscosity better represents a remarkable driving ability. In the case of low viscosity, the driving ability can be shown to be stronger than the actual pressure. Rather than the expression that the maximum pressure of the UHPLC apparatus is 100 MPa, it is better to express that the analysis method is equivalent to 185 MPa as the normalized pressure. It is convenient to use 1 mPa.Math.s as the reference for the viscosity when expressing the equivalent pressure. p.sub.η is equivalent to 100 MPa at 10.sup.11s.sup.−1, and p.sub.η s equivalent to 1 MPa at 10.sup.9s.sup.−1.
[0111] When p.sub.η is viewed at a micro level, the linear velocity u.sub.0 when the mobile phase flows through the gap between the filler particles is influenced by the viscosity η. This can also be seen from the fact that even though u.sub.0 is constant, ΔP increases proportionally to η (Equation 4). In other words, ΔP is represented in units of Pa because the unit of η contains Pa. The unit Pa of pressure or stress is a combined unit indicated by kg.Math.m.sup.−1.Math.s.sup.2. It is thought that the unit of mass, kg, is found in the separation theory of chromatography because of the existence of a viscosity. p.sub.η is defined as a physical quantity that is not affected by viscosity. The unit thereof is s.sup.−1. Therefore, when the normalized pressure p.sub.η is used instead of the pressure, the separation theory of chromatography can be expressed only in units of length and time, that is, m and s.
[0112] Newtonian fluids have similar physical quantities. For example, when a 1-mm gap between two separate plates is filled with a liquid, one of the two plates is fixed, and the other plate is moved in the longitudinal direction, a velocity gradient occurs in the normal direction The shear rate (s.sup.−1) is a physical quantity obtained by dividing the linear velocity (m/s) by the interval (m). The proportional coefficient connecting the shear rate (s.sup.−1) and the shear stress (Pa) is the viscosity η(Pa.Math.s). When the shear stress is considered to be due to the presence of viscosity, it is not necessary to incorporate viscosity into the theory, and it is sufficient to deal with only the shear rate. Referring to the units, it is possible to recognize that p.sub.η corresponds to the shear rate.
[0113] Shear-driven chromatography (SDC) utilizes a shear rate between two plates, but does not particularly require viscosity for formulation. In SDC, the average u.sub.0 in the axial direction is ½ times the relative movement speed of the plates. It is thought that it possible to visualize the high-speed separation performance of HPLC and SDC in a unified manner without using viscosity. The shear rate of the SDC describes the gradient along which the linear velocity is distributed from the movement velocity to zero toward a second flat plate that is stationary from a first flat plate that is movable. The shear rate (s.sup.−1) represents the change in linear velocity (m/s) per interval d (m) between two plates. On the other hand, when the normalized pressure p.sub.η (s.sup.−1) of HPLC is microscopically viewed, it exhibits the behavior of the linear velocity between the filler particles. In other words, it can be considered that it expresses the linear velocity distribution of the mobile phase flowing along the center between the stationary particles. In other words, the linear velocity in the axial direction has a microscopic gradient in the radial direction. The micrometer in this case is the size order of the distance between the particles. In HPLC, u.sub.0 is the average linear velocity, and the viscosity η is the flowability of the mobile phase (Equation 4). Assuming that the normalized pressure p.sub.η is caused by the micro-order inter-particle linear velocity distribution η of HPLC, it is considered that the shear rate and the normalized pressure p.sub.η are homogeneous indices corresponding to each other. Using p.sub.η, which reflects the micro velocity gradient of the axial linear velocity, which appears in the radial direction, it is possible to uniformly visualize the high-speed separation performance of HPLC and SDC without the need for viscosity. In addition, with regard to the unification of HPLC and SDC, it is noted again that the speed-length product Π is useful because it is a variable that does not affect both the viscosity η and the column permeability K.sub.V.
Full-Logarithmic Three-Dimensional Graph Representing Column Permeability
[0114] The diameter of particles d.sub.P has two working aspects for H (Equation 3) and ΔP (Equation 4). In Patent Literature 3, the N-Π graph was represented under ideal conditions to show the effect on H when the d.sub.P becomes ½ times. In addition, to show the effect of d.sub.P on ΔP, the impedance time t.sub.E was introduced to represent the t.sub.E-ΔP graph while limiting to the Opt. method.
[0115]
[0116]
[0117]
[0118] Since the cliff cross section n(u.sub.0) is reflected as the inverse of H(u.sub.0), i.e., a mirror image, the influence of d.sub.P can be visualized. After all, using
[0119] Even in a monolithic column that cannot be expressed simply by d.sub.P, in the case of a K.sub.V index, the pressure-related characteristics can be expressed by a graphical representation. In addition, even though the monolithic column cannot be expressed by d.sub.P, the monolithic column can be expressed as a cliff cross section in the case of n(u.sub.0).
[0120] For reference, the definition of the impedance time t.sub.E will be described again (Equation 26). By expressing the K.sub.V outside the full-logarithmic three-dimensional graph, and looking at the beginning and end of Equation 26, it can be seen that the normalized pressure p.sub.η is expressed on the principal x-axis instead of the speed-length product.
[0121] Here, the separation impedance E is a variable obtained by dividing H.sup.2 by K.sub.V. Fundamentally, it is seen that t.sub.E is a variable obtained by dividing E by p.sub.η. Since H is a function of u.sub.0 and d.sub.P, and KV is a function of d.sub.P, t.sub.E can also be expressed as a three-variable function of u.sub.0 and d.sub.P, and p.sub.η.
[0122] The three-variable function N(u.sub.0, L, dp) maintains three degrees of freedom and can be expressed as N(u.sub.0, p.sub.η, d.sub.P). The full-logarithmic three-dimensional graph as shown in
[0123] Patent Literature 3 shows a graph with a vertical axis of t.sub.E(s) and a horizontal axis of ΔP, which is related to the definition of UHPLC. In the case of changing the horizontal axis from ΔP(MPa) to p.sub.η(s.sup.−1), it is not necessary to take into account the influence of η, and UHPLC can be distinguished from HPLC in a more desirable manner. One effect of p.sub.η will be described below. The square N.sup.2 of the number of theoretical plates will be described as Equation 27 below, but when the vertical axis is the inverse of t.sub.E(s), that is, N.sup.2 per unit time, it becomes a graph showing the correlation thereof. Interestingly, both the vertical axis t.sub.E.sup.−1 and the horizontal axis p.sub.η of the graph for distinguishing UHPLC are unified only in terms of time, s.sup.−1.
Genuine Full-Logarithmic Three-Dimensional Graph
[0124] Since the scales of the axes show relative relationships, when the three axes in
[0125] In addition, referring to Equation 21, it can be seen that N.sup.2 is proportional to each of to and p.sub.η. This proportional relationship can be described by briefly referring to
[0126]
[0127] In
Introduction of Theoretical Plate Square Number Λ
[0128] Although described in Patent Literature 3,
[0129]
[0130] The behavior of to is similar to that of Π. When log t.sub.0 is moved right by +2, since the scaling factor 1/√2 is applied to the axis, +√2 goes forward on the graph. In a triangle with an apex angle of about 35.3°, the height log N rises by +1. Since +2 in log t.sub.0 corresponds to +1 in log N, log N=(½) log t.sub.0+C, that is, N.sup.2 is proportional to t.sub.0. The term “about 35.3° ” is θ obtained from the tan θ with the base of √2 and the height of 1. Although the flat plate of
[0131] Let N.sup.2 be the square of the theoretical plate number Λ and let Λ be the z-axis of the logarithmic three-dimensional graph.
Λ≡N.sup.2 [Equation 27]
[0132] A good feature that N is proportional to L is difficult to understand, but a good relationship that Λ is roughly proportional to to can be visualized. Similarly, Π is roughly proportional to Λ like t.sub.0. Although it is expressed as being roughly, but in the case of the flat plate model the term “roughly” will be replaced with the term “strictly” . The scaling factor 1/√2 applied to the scales of the to axis and the Π axis is relative. In addition, the scale, including the log N axis, is multiplied by √2, and thus along the log to axis and the log Π axis, it gently rises in the landscape of √2 log N, with a trajectory like traversing a slope. However, by introducing Λ, only the scale of is the z-axis is further scaled up by √2 times, and thus the notation of 45°-climbing along the log Π-axis (
[0133] Therefore, a flat plate with a steep slope of about 54.7° was adopted along the √2 log L axis, which becomes a schussing trajectory.
Visualization Approach
[0134] In order to visualize the separation performance, a description will start with H(u.sub.0) of the van Deemter plot, which is a source of separation performance. Since H(u.sub.0) is a u.sub.0 -dependent function, the horizontal axis inevitably becomes a graph of u.sub.0. The vertical axis indicating the separation performance is intended to set with N having the larger-the-better characteristic. However, when H(u.sub.0) having the smaller-the-better characteristic is used as it is, there is a concern of interfering with the user intuition. To help that intuition, n(u.sub.0) having the larger-the-better characteristic is introduced (Equation 2). n(u.sub.0) is the inverse of H(u.sub.0) and is a useful variable for visualization as described below. As can be seen from Equation 2, as the input variable N, L as well as u.sub.0 is required. Therefore, the input variable of the three-dimensional graph becomes the base plane (u.sub.0, L). As a result, the z-axis of the three-dimensional graph is represented by the output variable N, and the three-dimensional graph takes the form N(u.sub.0, L). Here, L serves as an extensive variable for N.
[0135] Next, there may be a desire to visualize the relationship between high separation performance and high speed. In the KPL method, t.sub.0 is used to express high speed. For the high speed, since t.sub.0 has the smaller-the-better characteristic, so for example, the inverse hold-up frequency v.sub.0 (Hz) of t.sub.0 can be introduced as a variable for a larger-the-better characteristic.
v.sub.0≡t.sub.0.sup.−1 [Equation 28]
[0136] v.sub.0 refers to the number of hold-up times t.sub.0 that can be counted per second, and the larger the faster. It is also possible to use v.sub.0 having the larger-the-better characteristic as necessary, but in the present invention, t.sub.0 having the smaller-the-better characteristic is used as an index indicating high speed, as an extension of the KPL method. The KPL method expresses the correlation between the high separation performance N and the high speed t.sub.0 as a t.sub.0-N graph, which means that it takes time to obtain high separation performance.
[0137] At first glance, it seems that there is no relationship between the aforementioned three-dimensional graph N (u.sub.0, L) and the t.sub.0-N graph of the KPL method. However, it is found that t.sub.0 can be obtained by expressing the base plane (u.sub.0, L) of the three-dimensional graph with a logarithm. Since t.sub.0 is a variable obtained by dividing L by u.sub.0, it is visualized by rotating the axis using the logarithm through the LRC transformation. In other words, the landscape that appears on the three-dimensional graph N(u.sub.0, L) remains as it is, and a new coordinate axis to appears through the LRC transformation. Therefore, t.sub.0 can be measured by only transfoming the coordinate axis. Interestingly, as a by-product, Π orthogonal to the logarithmic axis t.sub.0 was also found. This velocity-length product Π is a variable proportional to the pressure loss ΔP. Therefore, even though the landscape showing high separation performance is common, the logarithmic base plane (U, t.sub.0) to can be obtained by simply rotating the axis from the logarithmic base plane (u0, L), and at the same time, the high speed t.sub.0 and the pressure-related index Π can be visualized.
[0138] In addition, the z-axis N of the three-dimensional graph may remain as an antilogarithm, but since N is proportional to L, the gradient of the landscape, which is represented as N of the z-axis in a logarithmic notation, appears as 1 along L. This is also a very good feature.
[0139] Incidentally, although the column permeability K.sub.V is an important constant that characterizes the filler in addition to H(u.sub.0), it is considered to be a completely independent variable from the separation performance described so far. However, in practice, in the pressure-driven chromatography (PDC), since the upper limit ΔP.sub.max of ΔP exists, it seems that there is no choice but to consider K.sub.V indirectly. In the case of a shared-driven SDC, it may be sufficient to deal with Π orthogonal to t.sub.0 in logarithmic notation. However, since ΔP.sub.max is present in the PDC, it is necessary to analyze the factor in detail along the Π axis in the logarithmic notation.
Effect of K.SUB.V
[0140] In the case that n(u.sub.0) is constant, i.e., an n.sub.max flat plate model, in
[0141] The effects of K.sub.V will be described with reference to
[0142] The K.sub.V indicates the column permeability. For example, because a monolithic column has a relatively high liquid permeability, the value of the K.sub.V is large, and the origin of the log p.sub.η is relatively located on the positive side on the Π axis. Conversely, at a diameter of particles of 2 μm, the value of K.sub.V is relatively small, and the origin of log p.sub.η is pulled in a relatively negative direction. It is considered that the movement of the origin of log p.sub.η is attributed to K.sub.V, and the degree of influence of K.sub.V can be visualized by the three-dimensional graph.
Separation Impedance
[0143] In fact, in order to represent the image of the separation impedance E, a flat plate model of n.sub.max of a full-logarithmic t-type three-dimensional graph was prepared. The term “n.sub.max” is the inverse of H.sub.min expressed in Equation 14 (Equation 29).
[0144] In an ideal formula including a diameter of particles, it can be seen that n.sub.max is inversely proportional to d.sub.P. When the diameter of particles is 2 μm, the n.sub.max becomes 2 times larger and better compared to the case of 4 μm. In addition, it can be seen that the height of the cliff cross section at the log L=0 intercept is 2log n.sub.max in the flat plate model of the three-dimensional graph with the z axis Λ. Here, a ridge-profiling function f(u.sub.0) will be defined as a preparation (Equation 30).
n(u.sub.0)≡n.sub.maxf(u.sub.0={H(u.sub.0)}.sup.−1 [Equation 30]
[0145] Since n.sub.max has the maximum value, the value range of f(u.sub.0) is 1 to 0, and when u.sub.0 is u.sub.opt, n.sub.max, which shows a ridge, can be obtained. In addition, f(u.sub.0) is the inverse of the normalized function H(u.sub.0)/H.sub.max which is a division of H(u.sub.0) by H.sub.min. H(u.sub.0)/H.sub.min, which is the source of the reciprocal, can be called the valley-profiling function, and the value range is 1 to +∞.
[0146] Herein above, the cliff cross section of the z-axis log Λ on the √2 log u.sub.0 axis has been described, and it has been understood that the elevation of the cliff cross section, 2 log n.sub.max, is ideally dependent on the diameter of particles d.sub.P (
[0147]
[0148] First, the height of the z-axis at the origin of log Π=0 is determined to be 2 log n.sub.max. The horizontal axis shown in
[0149] In
[0150] This relationship can also be represented by a formula. Equation 31 shows the contribution of the diameter of particles d.sub.P to the z-axis direction. Terms including a, b, and c are constants.
log Λ=2 log n.sub.max=−2 log d.sub.P−2 log(a+2√{square root over (bc)}) [Equation 31]
[0151] On the other hand, the contribution to the log Π axis direction is shown by Equation 32. Similarly, the term including (φP is a constant.
[0152] When the diameter of particles d.sub.P increases, the deterioration of Λ in the z-axis direction of −2 log d.sub.P is offset by a change in log K.sub.V of 2 log d.sub.P. The reason will be described. Since the flat plate model has a 45° gradient on a trajectory like traversing a slope, when transforming the constant log p.sub.η, it increases the effectiveness of log Π by 2 log d.sub.P, which is the origin shift of log K.sub.V , in the positive direction
[0153] Conversely, even though the diameter of particles is reduced and the 2log d.sub.P is increased in the z-axis direction, since the origin of the log p.sub.η is pulled by 2log d.sub.P in the negative direction, the log Π is decreased and is eventually offset. This illustration shows the effect of adjusting the trajectory like traversing a slope to have a gradient of 45°. Since it climbs the flat plate with the trajectory like traversing a slope along the log Π axis, and the flat plate has a good gradient of 45°, in an ideal diameter of particles model, even though the horizontal component log K.sub.V shifts, the shift will be equal to the change in the z-axis log Λ.
[0154] The landscape is formed only by n(u.sub.0) of a first filler characteristic and is closed in a description up to Π. A may be introduced into the description which has been given so far. However, the pressure-driven PDC cannot avoid the pressure loss. Accordingly, although it is originally independent from the first filler characteristic, K.sub.V of a second filler characteristic must be considered. Secondarily, a criterion of p.sub.η is required, and it is believed that a description about the shift on the log Π axis is also necessary.
[0155] The idea of comparing K.sub.V to H.sup.2 is separation impedance E. H is the inverse of n, and n(u.sub.0) is represented by n.sub.max. The height of the cliff cross section of the flat plate model is n.sub.max constant, but it can be extended by the ridge-profiling function f(u.sub.0) to place the maximum point n.sub.max of u.sub.opt on the log u.sub.0 axis. The flat plate with Λ as the z-axis had a gradient of about 54.7° along the log L axis, but the ridge of u.sub.opt is drawn by f(u.sub.0). It is also useful to calculate E(u.sub.0) when dealing with fully porous particulate fillers, but it is also meaningful to understand n.sub.max and K.sub.V as they are, as shown in
[0156] High speed and high separation performance have been studied to understand UHPLC, but the contribution of the diameter of particles is offset in terms of separation performance and pressure characteristics. Ultimately, the Opt. method was used to devise a three-dimensional graph method that could extend the Knox-Saleem limit concept that there is an optimal diameter of particles for arbitrary pressure loss, to a variety of fillers.
[0157] In addition, it was found that there are two types of factors related to high sensitivity of UHPLC. One is the so-called semi-micro LC factor that reduces the cross-sectional area of the column, and the other is the contribution of the height-length product Σ newly introduced as a sensitivity index. Ideally, the former semi-micro LC does not affect the separation performance, but Σ has a reciprocity relation with N of the separation performance. The diameter of particles needs to be reduced to improve Σ having the smaller-the-better characteristic under the condition in which a constant N is secured. To visualize this relationship, a three-dimensional graph with N and diameter of particles as the input base plane and Σ as the z-axis was displayed. In addition, by replacing the z-axis on the same base plane with a pressure loss, it was possible to visualize the degree of increase in pressure linked to Σ. It was found that the miniaturization of fillers characterizing UHPLC and the application of the pressure corresponding thereto were indispensable to improve the sensitivity performance of UHPLC.
Variable Not Requiring Pressure Unit
[0158] In the first half of Equation 26, tE is H.sup.2/Π and does not require units such as Kg for mass and Pa for pressure. In that case, ΔP, η, K.sub.V, or p.sub.η in the second half of Equation 26 are unnecessary. In addition, E(u.sub.0) was introduced as a variable for mixing H and K.sub.V while taking into account d.sub.P, but E(u.sub.0) is also unnecessary when K.sub.V is taken as a secondary shifting variable for dealing with pressure, as described above. However, the usefulness of the idea of t.sub.E=t.sub.0/Λ remains to take advantage of the trajectory like traversing a slope. Here again, Π has units of time and length, and is uniquely found as a variable orthogonal to t.sub.0 on the logarithmic axis of the base plane. In other words, the velocity-length product Π is a product of the LRC transformation associated with u.sub.0, L, and t.sub.0. Furthermore, Π can be considered as a driving index that can be used in common for PDC and SDC, instead of ΔP and p.sub.η.
[0159] The Opt. method says that for every u.sub.0, there exists each d.sub.P at which u.sub.0 becomes u.sub.opt. This idea implies that ideally the u.sub.0 axis has one-to-one correspondence with d.sub.P. In other words, it means that the three degrees of freedom of the operational input variables (u.sub.0, L, d.sub.P) can be reduced to a base plane (u.sub.opt, L) with two degrees of freedom. In the case of the base plane (u.sub.opt, L), d.sub.P is bound to u.sub.opt, and when u.sub.opt is specified, d.sub.P is determined to be inversely proportional (see Equation 13).
[0160] The add-on speed-up method illustrated in
[0161] The mechanism of ΔP is somewhat complex. In the add-on speed-up u.sub.sub method, dp and L are constant. Therefore, K.sub.V remains unchanged, and Π and ΔP increase slightly due to the contribution of u.sub.0. On the other hand, when the speed-up is performed while increasing the linear velocity to u.sub.0 by the Opt. method so that L is constant and same, it is an optimization method in which d.sub.P is linked to u.sub.0 or u.sub.opt and is miniaturized. The K.sub.V also deteriorates and decreases due to this miniaturization. In the case of the u.sub.opt method, when u.sub.opt is increased, ΔP is doubled and worsened by due to both Π and K.sub.V. However, the advantage that N is slightly improved and increased due to the miniaturization of the filler is obtained.
Comparison of t.SUB.E .Between u.SUB.opt .Method and u.SUB.sub .Metho
[0162] The u.sub.sub of the add-on speed-up method is practical, but is slightly deteriorated in terms of high-speed and high separation performance as compared to the ideal u.sub.opt method. A method of quantitatively grasping this gap is devised. When t.sub.E is introduced into Equation 26, Equation 33 is obtained.
[0163] As a question, imagining a base plane (u.sub.0, L), given an arbitrary starting point O(u.sup.0, L), the optimum linear velocity u.sub.opt and the optimum diameter of particles d.sub.Popt associated with u.sub.opt are determined. In
[0164] The calculation procedure of the differential coefficient dt.sub.E/du.sub.0 is expressed by Equation 34. As a result, it is expected that there will be a difference between the u.sub.sub method in which d.sub.P is fixed to d.sub.Popt and the u.sub.opt method in which d.sub.P is linked to u.sub.0.
[0165] The second term of Equation 34 does not differ between the u.sub.sub method and the u.sub.opt method. It can be seen that the difference occurs especially in the differential coefficient dH/du.sub.0 of the first term.
[0166] First, in order to obtain dH/du.sub.0 from Equation 3, partially differentiation with u.sub.0 and d.sub.P will be performed, resulting in the expression of Equation 35.
[0167] In the case of the usub method, since d.sub.P is constant, dd.sub.p is 0. D.sub.P is a fixed value that maintains dP.sub.opt obtained from Equation 13
[0168] The dH/du.sub.0 of the u.sub.sub method is obtained by inputting dd.sub.P= and Equation 36 into Equation 35 (Equation 37).
[0169] As it can be seen from
[0170] On the other hand, in the case of the u.sub.opt method, as shown in
[0171] In addition, dd.sub.P turns into Equation 39 through variable conversion.
[0172] The dH/du.sub.0 of the u.sub.opt method is obtained by inputting Equation 38 and Equation 39 into Equation 35 (Equation 40).
[0173] The first term of Equation 40, derived from du.sub.0, disappears. The second term, which is influenced by dd.sub.P, remains, and dH/du.sub.0 is always negative. That is, due to the contribution to of filler miniaturization, H decreases and improves. As can be seen from Equation 14, (a+2√ab)d.sub.P(u.sub.0) is a function of u.sub.0 that is also called H.sub.min (u.sub.0), and outputs the minimum value of H at a certain u.sub.0. H.sub.min (u.sub.0) is a unique concept of the u.sub.opt method, conceived for the ideal condition in which d.sub.P is linked to u.sub.0, as expressed by Equation 38. Equation 31 is obtained from Equation 40.
[0174] For convenience, H.sub.min (u.sub.0) can be defined as Equation 42.
H.sub.min(u.sub.0≡(a+√{square root over (bc)})d.sub.P(u.sub.0) [Equation 42]
[0175] However, it is desirable to define H.sub.min(u.sub.0) such that it does not depend on the coefficients of equations such as Equation 3. Therefore, the height equivalent to a theoretical plate is first represented as a landscape of a two-variable function H(u.sub.0, d.sub.P). In addition, since u.sub.opt, which gives the minimum value H.sub.min of H, is constrained as a function u.sub.opt (dP) of d.sub.P, u.sub.opt (dP) in the base plane (u.sub.0, d.sub.P) depicts a curvilinear trajectory. H.sub.min (u.sub.0) traces the minimum value on this trajectory. In other words, the original definition of H.sub.min (u.sub.0) is the valley line connecting the lowest points along u.sub.0 in a landscape.
Summary of High-Speed High Separation Performance
[0176]
[0177] The add-on speed-up method illustrated in
[0178] As can be seen from the comparison between Equation 37 and Equation 40, the u.sub.opt method improves high speed and high separation performance by allowing d.sub.P to be changed. Regarding this, to understand the subtle differences, visualization based on the full-logarithmic ΠtΛ-type three-dimensional graph illustrated in
[0179] Although pressure is not mentioned in this description, as disclosed in Patent Literature 3, the process of miniaturizing d.sub.P in the u.sub.opt method completely offsets the improvement of H and the deterioration of K.sub.V . Since the offsetting effect of such d.sub.P is known, the analysis according to Equation 33 can be performed using Π as a driving index without wonying about the influence of pressure. Eventually, t.sub.E could be calculated without considering pressure.
[0180] The impedance time is t.sub.E, but there is a similar variable which is a plate time t.sub.P (Equation 43). T.sub.P is determined with a certain u.sub.0 fixed. Fixing u.sub.0 to u.sub.opt is a naive idea. Since t.sub.P is an analysis method assuming that u.sub.0 is fixed, when viewed on the full-logarithmic ΠtΛ-type three-dimensional graph illustrated in
[0181] On the other hand, as can be seen from the image illustrated in
Visualization of Four-Dimensional (4D) Graph
[0182] As one embodiment, addition of a particle diameter d.sub.P to a basic three-dimensional graph having a linear velocity u.sub.0, a column length L, and the theoretical number N of stages results in a four-dimensional graph, making visualization difficult. One challenge is how to visualize 4D graphs in an easily understandable way. For example, although
LRC Scope
[0183] First, instead of N, a three-dimensional graph with a theoretical number of stages n(u.sub.0, d.sub.P) per unit length is displayed. Here, n on the z-axis is a characteristic function that is significantly affected by each of the input variables u.sub.0 and d.sub.P of the base plane. This three-dimensional graph is represented on a full-logarithmic axis. The reason why the z-axis is represented by n instead of N is that n is considered as a more fundamental characteristic function, as can be seen from the fact that N is two-dimensionally obtained by multiplying the extensive variable L by n.
[0184] Here, n(u.sub.0, d.sub.P) can be expressed in a full-logarithmic graph as shown in
[0185] In the LRC scope, the user first specifies, for example, an n-u.sub.0 card with a particle diameter of 2 μm, and extracts one card from the three-dimensional graph n (u.sub.0, d.sub.P). For the n-u.sub.0 card, the LRC scoop is a function that adds the log L axis in a horizontal direction, perpendicularly to the card, thereby generating a new full-logarithmic three-dimensional graph. The display of the output is exactly as shown in
[0186] When the user specifies a particle size of 3 μm or 5 μm, the corresponding n-u.sub.0 card is extracted, and N(u.sub.0, L) three-dimensional graphs for respective particle sizes can be generated by the LRC scope function. The LRC scope is a function that adds the L-axis to make a two-variable function, in contrast that the n-u.sub.0 card is a single-variable function n (u.sub.0) having the z-axis n By expanding one input variable u.sub.0 to the base plane (u.sub.0, L) of a two-variable function, the z-axis is expanded from n to N. By adding the L axis to the n(u.sub.0) card of the cliff cross-section, it is possible to inflate it to a hilly terrain landscape N(u.sub.0, L) (see
[0187] The LRC scoop function generates a hilly terrain N(u.sub.0, L) from one n-u.sub.0 card.
[0188] As can be seen from
[0189] By the way, since the base plane of the N(u.sub.0, L) full-logarithmic three-dimensional graph of each particle diameter is (u.sub.0, L) coordinates, there are also (1/√2) Log Π axis and (1 /√2) Log t.sub.0 axis at positions rotated counterclockwise by 45° from the log u.sub.0 axis and the log L axis that are orthogonal to each other, as shown in
Microstructure Parameter d
[0190] As shown in
Ridge Line of n
[0191] In
[0192] To examine the characteristics of the ridge line, the partial differential coefficient ∂.sub.n is defined by Equation 44.
[0193] Equation 44 is a three-dimensional graph illustrated in
[0194] The base plane coordinates (u.sub.0, d) of the ridge line and the bottom plane coordinates (u.sub.0, d) of the valley line are the same when viewed from above. When H (u.sub.0, d) can be expressed as Equation 3, the trajectory of the ridge line or valley line follows Equation 13, and the ordinate coordinates d will form an inversely proportional curve with respect to the abscissa u.sub.0. This is true for true number notation, but when the d-u.sub.0 graph is displayed on the logarithmic axis, the ridge line becomes a straight line (
[0195]
Interpretation of Scaling Scale Factor
[0196] One of the cards is extracted, and the LRC scope is applied thereto. Then, a three-dimensional graph of (u.sub.0, L, N) appears. For example, it is a full-logarithmic graph of (u.sub.0, L, N) for d=2 μm. As described above, a 45° counterclockwise logarithmic axis (Π, t.sub.0) can be drawn on the same plane in the base plane (u.sub.0, L). However, the log Π axis and the log t.sub.0 axis are the products of multiplication by the scale factor 1/√2, and the z axis is log N (see
[0197] For example, when log L is 1 at log u.sub.0=1, the length of the diagonal corresponding to log Π is only √2 when measured on the graph. Therefore, the meaning of the scaling scale factor is that since the log Π of the length √2 is read as 2(u.sub.0×L=Π; 10×10=100), it is written as (1/√2) log Π axis, which means that what was originally 2 is multiplied by 1/√2 and drawn to a length of √2.
PPP Contour Diagram
[0198] Next, to make the scale factor of the log Π axis and the log to axis equal to 1, all the ticks of the logarithmic axes of the three-dimensional graph are shrunk to 1/√2 times. At this point, the 1√2 log u.sub.0 axis, √2 log L axis, and √2 log N axis are obtained (
Transparent PPP Contour Map
[0199] Going back to the origin, i.e.,
High-Speed High Separation Resolution under Constant Pressure Loss
[0200] A scenario is considered in which the user wants to observe the behavior of the particle diameter from the viewpoint of high-speed high separation resolution under a constant pressure loss condition. For convenience, the microstructure parameters associated with viscosity is particularly set to d.sub.V. In addition, microstructure parameters originating in N, n, or H in the z-axis direction are also referred to as d.sub.H. The point of the present application is to treat d.sub.V and d.sub.H independently. In the case of the aforementioned monolithic column, the skeleton size corresponds to d.sub.H and the macropore size corresponds to d.sub.V. In the case of the core-shell column, the shell thickness corresponds to d.sub.H, and the particle diameter corresponds to d.sub.P or d.sub.V. The present paragraph starts with the point in which the d axis of
[0201] When the user specifies a certain d.sub.V, a landscape n(u.sub.0, d.sub.V) as shown in
[0202] Since the base plane (u.sub.0, L) of the PPP contour map has 2 input variables, the degree of freedom is 2. When the optimum flow velocity u.sub.opt is selected in advance in the PPP contour map of a certain d.sub.V, the degree of freedom can be reduced from 2 to 1. Therefore, L becomes a variable that is dependent on Π. Since that the degree of freedom is 1 can be expressed as a certain variable, a one-variable scheme based on Π can be made. In reality, the one variable can be specified as either t.sub.0 or L. However, in the present embodiment, it is convenient to make Π variable because p.sub.η is fixed. The simple reason for choosing u.sub.opt is that at each d.sub.V, at least the maximum value n.sub.max is obtained for any L, as long as u.sub.opt is selected. In other words, the advantage of broadly selecting u.sub.0 rather than u.sub.opt for a simple argument is that when the upper limit is applied to p.sub.η on the Π axis, another suitable u.sub.opt can be selected in the base plane (u.sub.0, L) region in which u.sub.opt cannot be selected. However, in the case of aiming for high speed, although the user wants to select a flow velocity u.sub.0 higher than u.sub.opt of a certain d.sub.V, there are certainly a filler whose optimum flow velocity u.sub.opt is the flow velocity u.sub.0, and its n.sub.max. This logic is similar to the u.sub.opt approach in which when different particle sizes are allowed, the optimal particle size and the optimum u.sub.opt under pressure constraints can be obtained. Conversely, in the case of aiming for high separation resolution, u.sub.0 that is slower than u.sub.opt of a certain d.sub.V is selected to extend L. However, the same insight can be considered because there are certainly a large filler d.sub.V whose u.sub.0 is u.sub.opt and its n.sub.max. Roughly speaking, the logic is that for each flow velocity u.sub.0, there is certainly a filler d.sub.V whose optimum flow velocity u.sub.opt is the flow velocity u.sub.0. After that, the idea is to adjust the degree of freedom of 1 to Π or L.
Total Porous Particles
[0203] Let's take the case where the filler such as silica gel is total porous particles. According to Equation 13, log u.sub.opt is log u.sub.AH-log d.sub.P. u.sub.AH is √(b/c), which is called Antia & Horvath's velocity coefficient named after the name of the discoverer. Since u.sub.AH[m.sup.2/s] is a constant, log u.sub.opt is scaled on the log u.sub.0 axis as a function of the particle diameter d.sub.P (Equation 46). By the way, u.sub.AH is the same constant as U.sub.min described in Patent Document 3. In addition, the dimensionless coefficient a+2√(bc) of Equation 14 is called the Antia & Horvath's height coefficient h.sub.AH, which is the same constant as h.sub.min as described in Patent Document 3.
[0204] On a transparently superimposed PPP contour map, when the variable d.sub.P is varied, K.sub.V is a function of d.sub.P and affects log Π. In the present embodiment, since log p.sub.η is a constant, d.sub.P uniquely determines log Π via log K.sub.V. Equation 47 is obtained from Equation 25.
logΠ=logp.sub.η+logK.sub.V==logp.sub.η+2logd.sub.P−logϕ.sub.P [Equation 47]
[0205] Similarly, d.sub.P also affects u.sub.opt on the basis of log u.sub.AH, which is a constant. u.sub.opt which is a function of d.sub.P uniquely determines the coordinate on the log u.sub.0 axis. Therefore, the parameter d.sub.P is not visible on the transparent PPP contour map, but the trajectory thereof appears in a bird's-eye view (
[0206]
[0207] That is, when p.sub.η is specified, the high-speed high separation resolution trajectory (t.sub.0, Λ) appears accordingly, and the various values u.sub.opt, L, and Π can also be read. However, even though d.sub.P is the cause and generates each point on the trajectory, d.sub.P cannot be directly expressed in coordinates because it serves as a parameter.
[0208] For total-porous particles, d=d.sub.P, and K.sub.V and n.sub.max are offset. K.sub.V is proportional to the square of d, and n.sub.max is inversely proportional to d.sub.P. When this equation is applied to a transparent superimposed PPP contour map, the effect of finely refining d.sub.P disappears. The scale factor √2, which is a symbolic scale factor in the LRC scope, and the adjustment of the z-axis to Λ on the basis of the gradient of the trajectory like traversing a slope influence this mechanism. The results are summarized in Tables 3 to 5.
[0209] The impedance time tE of Equation 26 is constant. t.sub.E is the ratio of hold-up time t0 and Λ, and the reason of t.sub.E being constant is that the trajectory like traversing a slope along the time axis has an inclination of 45° in a flat plate model. It is ingenious to assume that the flat model is the best ideal state. This ingenuity is assumed to be equivalent to the u.sub.opt method. Therefore, the separation impedance E(u.sub.0) with respect to the Knox & Saleem limit based on the u.sub.opt method is a good indicator (Equation 26). The particle size d.sub.P of total-porous particles influences K.sub.V and influences n.sub.max or H(u.sub.0) via u.sub.opt. As shown Equation 26, the PPP depiction shows that the action is a performance index expressing that the numerator and the denominator of a fraction are canceled by K.sub.V and the square of H.
[0210] The square of N in Equation must be Λ. However, a similar statement can be made for Σ, which is a sensitivity performance index so that the trajectory like traversing a slope can be adjusted to an inclination of 45° by squaring. Originally, N is derived from nL, and Σ is derived from HL. When the z-axis in
TABLE-US-00003 TABLE 3 List of result of transparent PPP contour map 1 d.sub.P u.sub.opt K.sub.V H.sub.min (×10.sup.−6 m) (×10.sup.−3 m/s) (×10.sup.15 m.sup.2) (×10.sup.−6 m) (×10.sup.−3 m.sup.2/s) 2 3.00 2.67 6.24 0.247 3 2.00 6.00 9.36 0.556 4 1.50 10.7 12.5 0.988 5 1.20 16.7 15.6 1.54
indicates data missing or illegible when filed
TABLE-US-00004 TABLE 4 List of result of transparent PPP contour map 2 d.sub.P (×10.sup.−6 m) L (×10 m)
(s) N (×10.sup.3) Λ (×10.sup.9) 2 82.2 27.4 13.2 0.173 3 277 139 29.6 0.878 4 658 438 52.7 2.77 5 1,280 1,070 82.3 6.77
indicates data missing or illegible when filed
TABLE-US-00005 TABLE 5 List of result of transparent PPP contour map 3 d.sub.P .sub.E
.sub.P E ΔP (×10.sup.−6 m) (×10.sup.−6 s) (×10
s) (×10.sup.3 m) (×10.sup.6 Pa) 2 0.158 2.08 14.6 50 3 0.158 4.68 14.6 50 4 0.158 8.31 14.6 50 5 0.158 1.30 14.6 50
indicates data missing or illegible when filed
Limiting Conditions of p.SUB.η in Ideal uopt .Method
[0211] Again, using the microstructure parameters d.sub.H and d.sub.V, the u.sub.opt method for the optimum flow velocity limited by the normalized pressure p.sub.η can be specified. H.sub.mincan be expressed as Equation 48 using the Antia & Horvath's height coefficient hAh as described above, and the microstructure parameter d.sub.H derived from H.
H.sub.min=h.sub.AHd.sub.H [Equation 48]
[0212] The u.sub.opt that produces H.sub.min is represented by Equation 49. This is the real number representation of Equation 46, but the microstructure parameter is denoted by d.sub.H.
[0213] In fact, although being unrelated to the u.sub.opt method, Equation 50 of K.sub.V, which is related to Equation 47, will be prepared. To distinguish from d.sub.H, the microstructure parameter for viscosity is set to d.sub.V as described above.
[0214] Using these, the hold-up time to in which d.sub.H and d.sub.V are mixed can be derived (Equation n51).
[0215] Similarly, N can be calculated (Equation 52).
[0216] Accordingly, the impedance time t.sub.E of Equation 26 can be obtained (Equation 53).
[0217] Here, when each of d.sub.H and d.sub.V is equal to the particle diameter d.sub.P, the left-hand side becomes a constant because d.sub.P is offset. Therefore, t.sub.E of total-porous particles does not depend on d.sub.P, and t.sub.E is constant as in Table 5. In addition, since d.sub.H and d.sub.V can be independently designed for the monolith column and the core-shell column, Equation 53 describes that when the viscosity-related d.sub.V is increased relative to the d.sub.H derived from H, t.sub.E can be reduced, which contributes to high-speed high separation resolution.
[0218] Furthermore, when the u0 of E(u.sub.0) that appears at tE of Equation 26, it becomes E.sub.opt of Equation 54.
[0219] When looking at Equations 53 and 54, it is considered that tE is given the
[0220] dimension of time by dividing the dimensionless E.sub.opt by p.sub.η [s.sup.−1]. The advantage of monolithic and core-shell columns is that d.sub.V can be set to be larger than d.sub.H due to flowability, since a smaller E.sub.opt is desirable.
[0221] Similarly, in Table 5, d.sub.H and d.sub.V are offset due to the fact that they are each equal to the particle diameter d.sub.P, which describes why E in Equation 54 is E constant.
Use of Flat Plate Model and Understanding of Deviation
[0222] As seen in
[0223] Since H.sub.minis a minimum value, β(u.sub.0) is a variable in a range of from 0 to 1, which is the deviation ratio between the actual landscape and the flat plate model. Slope B and Slope C in
[0224] E.sub.opt in Equation 54 can be extended to Equation 56 by using the β ratio.
[0225] Accordingly, t.sub.E can be expressed as Equation 57.
[0226] Therefore, when the normalized pressure p.sub.η is fixed, t.sub.E depends on u.sub.0. The dependence depends on the β ratio, which is the degree of attenuation of Slope B or Slope C. In addition, E.sub.opt is a constant for total-porous particles but varies depending on the ratio of d.sub.H to d.sub.V in the case of monolithic and core-shell columns. The operation in which Π can be changed by K.sub.V, i.e., d.sub.V, with p.sub.η fixed. Note that d.sub.V is introduced to explain the analogy with d.sub.H and d.sub.P, but if only Kv is known, it is not necessary to break particles down to d.sub.V.
[0227] A normalized velocity, v.sub.opt, is introduced to identify Slopes B and C (Equation 58). v.sub.opt is a simple dimensionless ratio representing any linear velocity u.sub.0, while regarding u.sub.opt as the reference line velocity.
u.sub.0=v.sub.optu.sub.opt [Equation 58]
[0228] Thus, for the base plane coordinates where v.sub.opt is greater than 1, the landscape is in a slope C region, which is suitable for high speed. Similarly, for normalized velocities where v.sub.opt is less than 1, the base plane coordinate point is on Slope B, which is suitable for high separation resolution. In a graph with z-axis n, the trajectory where v.sub.opt is 1 corresponds to the ridge line on a topographic map.
Finer Granulation of d.SUB.P
[0229] Suppose that the user simply considers a finer grain size of d.sub.P in a range of from 4 μm to 2 μm under a flat plate model Λ where Λ is indicated on the z-axis. According to Equation 43, n.sub.max, which is the reciprocal of H.sub.min, is doubled. The cliff cross section (log L=0) of the flat plate model Λ is four times higher since it is the square of n.sub.max. Next, the optimal linear velocity u.sub.opt is increased two times according to Equation 49. When the linear velocity Π is limited, L must be reduced to ½ times due to the effect of doubling u.sub.opt. Finally, the column transmittance K.sub.V decreases proportionally to the square of d according to Equation 50. When the normalized pressure p.sub.η is limited, the movable range on the log Π axis is further reduced, and L must be reduced excessively to ½ times or less.
[0230] This logical development can be read from the contour map of
[0231] In
[0232] base plane. The trajectory movement from 5 μm to 2 μm is projected on the √2 log L axis, and it is seen that L shrinks. In addition, the log to axis in
[0233]
[0234] In
[0235] In the same graph as in
Comprehensive Example of Flat Plate Model
[0236]
[0237] For simplicity, the understanding of Landscape Λ is aided by the introduction of the β-ratio in Equation 55, which is approximated by a flat plate model. The reason why the flat plate in
[0238] First, the only characteristic parameter is the z-axis height of the cliff cross-section, i.e., log n.sub.max.sup.2 because the flat plate model Λ has a constant gradient. Incidentally, in the flat plate model N, the height of the cliff cross-section is log nm (
[0239] Next, the viewpoint is shifted from the z-axis to the log Π axis. Cases are considered in which p.sub.η is limited to a certain value, like a case where there is an upper limit to the pressure drop. According to Equation 50, K.sub.V is proportional to the square of d.sub.V. As with the z-axis, when a new d.sub.V is ½ times the original d.sub.V, fluidity decreases such that K.sub.V becomes ¼ times. Since the case is a case where p.sub.η is constant, log Π decreases by log 2.sup.−2, or by 0.60.
[0240] Here, assuming total-porous particles, the microstructure parameters of d.sub.H and d.sub.V are equal to the particle diameter d.sub.P. Even though d.sub.P is reduced by ½ times and the cliff height of the flat plate is increased by 0.60, since the upper limit of the log Π axis is reduced by 0.06, the effect of d.sub.P is canceled out. This behavior can be seen in the cross-sectional view of log Λ-log Π with t.sub.0 fixed (
[0241] As shown in
[0242] On the other hand, when looking at changes from point A to point B to pint C in a projection view of log Λ-log t.sub.0, t.sub.0 is constant, and only log Λ changes up and down. In other words, even though the plat plate is raised with d.sub.P reduced to ½ times, since p.sub.η is limited, it slides down with the trajectory like traversing a slope, along the log Π axis. The amount of log Λ by ascending and the amount of log Λ by descending are offset. In the flat plate model Λ, since the slope along the t.sub.0 axis is 45°, the impedance time t.sub.E that is obtained by dividing to by Λ is constant.
Ohm's Law of Separation
[0243] As shown by Equation 59, it is well known that Dr. Knox compares this characteristic to Ohm's law. p.sub.η corresponds to voltage, E corresponds to resistance, and t.sub.E.sup.−1 corresponds to current. Since the current t.sub.E.sup.−1 indicates high separation performance per hour, the reciprocal of the impedance time is referred to as a separation current I.sub.Λ. A voltage p.sub.η is to be applied to obtain a larger current I.sub.Λ, but the separation impedance E resists. The dimension of Equation 59 is the reciprocal of time. Equation 59 is called Ohm's second law concerning separation. The normalized pressure p.sub.η is exactly the potential difference, and is referred to as the separation potential difference.
[0244] Here, since the equation is transformed as a flat plate model, u.sub.0 can be substituted by E.sub.opt obtained using u.sub.opt (Equation 54) or H.sub.min. In addition, because of the flat plate model, the gradient (log)/(log t.sub.0) is 1 because it is a trajectory like traversing a slope, and Λ is proportional to t.sub.0 as described above. In addition, since the product of p.sub.η and K.sub.V is Π, Λis also proportional to Π (Equation 26).
[0245] The flat plate model is an ideal model that provides optimum flow separation performance u.sub.opt at any u.sub.0, and the real landscape Λ attenuates for both slope B and slope C by maximizing the ridge line expressed by the β ratio. The separation impedance is defined as a function E(u.sub.0) of u.sub.0, but it is assumed that is extended to the function E(u.sub.0) after the concept of the optimal E.sub.opt is established.
[0246] Ohm's law also leads to other expressions. When Equation 26 is denoted as Equation 60, the left side is multiplied by the speed-length product Π and the right side is multiplied by the square of H, so that the equation of the separation current I.sub.Λ is obtained. Equation 60 is called Ohm's first law concealing separation. I.sub.Λ commonly appears in Equation 59, Π corresponds to the voltage, and the square of H corresponds to the electrical resistance Ω. Therefore, the separation voltage Π corresponds to the electromotive force that is the source of u.sub.0 and L, and the square of H can be referred to as the separation resistance Ω.
[0247] The unit of Equation 59 in the second law is [s.sup.−1], whereas the unit of the first law Π is [m.sup.2s.sup.−1]. The difference is due to the difference in whether the separation impedance E is defined to include the column permeability K.sub.V or the separation impedance E is defined with only the theoretical stage equivalent height H like the separation resistance Ω. In order to quantify the pros and cons of finer column filler, Dr. Knox wanted to take into account not only the improvement in H, but also the column permeability K.sub.V, which worsens flow resistance. The separation potential difference p.sub.η is nothing but the pressure difference ΔP that takes the viscosity η into account. On the other hand, note that the separation voltage Π is a characteristic of being divided into p.sub.η and K.sub.V like the relationship of u.sub.0 and L (Equation 25). It means that the effectively acquired separation voltage Π is affected by the K.sub.V difference for the same p.sub.η.
[0248] It can be said that regarding the Ohm's laws for Π and p.sub.η, respectively, while the former first law (Equation 60) is a basic formula that does not cover the flow characteristics of the filler material, the latter second law (Equation 59) is a more practical and explicit expression with a strong awareness of pressure loss. The second law is based on the pressure difference ΔP, and the first law is based on the column length L. Here, L is a simple extensive variable. Furthermore, Equation 60 is obtained by multiplying each of both sides of Equation 50 by K.sub.V. Therefore, it is assumed that the pressure is caused by K.sub.V. Equation 60 is called the first law because it is unnecessary to consider the pressure when considering separation. In addition, the reason why the separation current I.sub.Λ is defined as the ratio of Λ and t.sub.0 is that Λ and t.sub.0are roughly proportional to each other, and this property is significant.
[0249] Point C in
[0250] Under a condition in which Π is constant, the degree of freedom of the parameter t.sub.0 allows point C in
[0251] In Patent Document 2, the time extension coefficient μ.sub.N/t is introduced to quantify the approach to t.sub.opt. Since there is a coefficient of 2 in the definition formula of μ.sub.N/t , which means that the square of 2 is Λ, a new time elongation coefficient μ.sub.Λ/t can also be defined as an index equal to μ.sub.N/t. When t.sub.0 is greater than t.sub.opt, the effectiveness μ.sub.Λ/t is less than 1, but Λ can be increased by multiplying by a constant gradient Π. Patent Document 3 shows that this increase is a monotonic increase for t.sub.0, and there is an upper limit N.sub.sup. In other words, the square of N.sub.sup, is the upper limit Λ.sub.sup, which is the critical value.
[0252] On the other hand, Π is constant, and I.sub.Λ becomes maximum at t.sub.opt along the time axis. This is because the separation current I.sub.Λ is represented as Equation 61, and H.sub.min is obtained at u.sub.opt, that is, at the time of t.sub.opt, and it becomes the maximum value. A three-dimensional graph, such as landscape Λ is thought to be a representation method devised to visualize the Ohm's first law concerning separation.
Symmetry of Separation Performance and Sensitivity Performance
[0253] When Equation 11 is applied to Equation 60, the sensitivity performance Σ can be expressed as Equation 62. As described above, Ξ is the square of Σ, and Λ is the square of N.
[0254] Equation 62 is considered as the Ohm's first law concerning sensitivity. In this case, Π is the sensitivity voltage, the reciprocal of Ω is the sensitivity resistance, and I.sub.Ξ is the sensitivity current. When compared with Equation 60, it is found that Λ and Ξ are symmetric, and N and Σ are symmetric. The only difference is that the resistance of the separation law is Ω, whereas the resistance of the sensitivity law is the reciprocal of Ω. Accordingly, the tactics obtained by the separation performance display method such as the flat plate model can also be applied to the sensitivity performance display method. However, it should be noted that while the separation performance uses ridge lines and maxima, the landscape Σ and the landscape Ξ use valley lines and minima because these have the smaller-the-better characteristic. Accordingly, in the case of sensitivity performance, it is not a scheme in which a strong sensitivity voltage VI is applied to obtain a large amount of sensitivity current I.sub.Ξ. By dividing each of both sides of Equation 62 by K.sub.V, the Ohm's second law p.sub.η concealing sensitivity can be obtained. In this case, the constant of proportionality such as electrical resistance against I.sub.Ξ of the sensitivity potential difference p.sub.η is a value obtained by dividing the reciprocal of Ω by K.sub.V. For convenience, I.sub.Ξ may be referred to as the sigma current I.sub.Σ and I.sub.Λ may be referred to as the nucleotide current I.sub.N, but the subscript notation of Ξ and Λ is preferable.
[0255] In terms of symmetry, the pressure application coefficient μ.sub.Σ/P (CPA) and the time extension coefficient μ.sub.Σ/t (CTE), which indicate the effectiveness described in Patent Document 2, can also be defined for sensitivity performance (Equation63 and Equation 64).
[0256] This is because the coefficient 2 expressed as a formula has a characteristic in which the square of Σ is substantially proportional to Π and t.sub.0, like the separation performance N based on the u.sub.opt method (Equation 62). This is because the use of Λ and Ξ is highly convenient.
General Overview of Field of HPLC
[0257] The separation performance can also be displayed by using the separation resolution R.sub.S instead of N. The relationship between R.sub.S and the theoretical number N of stages, including the retention time difference of two components, will be described using the formula of √N (Equation 65).
[0258] Here, t.sub.2, t.sub.1, W.sub.2, and W.sub.1 are the retention times and total peak widths of peak 1 and peak 2, and W.sub.1=W.sub.2 is approximated by assuming that the adjacent base line widths are close. In addition, the formula N=16t.sub.2.sup.2/W.sub.2.sup.2 defining the theoretical number of stages, and the relational formula t.sub.i=t.sub.0(k.sub.i+1) of the retention time t.sub.i and the retention coefficient k.sub.i (where i=1, 2) are used. Here, t.sub.0 is the hold-up time. In addition, the separation coefficient is defined as α=k.sub.2/k.sub.1, and the elution is made in order of peak 1 and peak 2. Starting from the definition expression of R.sub.S of Equation 46, a well-known far-right expression is obtained. As can be seen from the expansion of the mathematical formula, since the separation resolution is considered to be isocratic elution, caution should be taken when using it for gradient elution. It is also necessary to bear in mind that a two-component system is considered, and it is more convenient to understand it as a one-component system, N, for the indication of separation performance as in the present application.
[0259] General HPLC separation methods starting from adsorption chromatography, including reversed-phase chromatography RPC, and ion-exchange chromatography IEC, including size-exclusion chromatography SEC, will be comprehensively described. Although the invention has been described basically with respect to the RPC, the invention is also applicable to the IEC. Therefore, the technical aspects of a high-speed amino acid analyzer AAA, which is, in principle, an IEC, are also covered in the present application.
[0260] Although the present invention is described from a fundamental theoretical point of view, it can of course be extended to applications. For example, although the embodiments of the present invention are based on isocratic elution, since isocratic elution is described, stepwise elution as well as gradient elution can be deduced. From the viewpoint of describing the migration behavior of solutes in a column, stepwise elution of two liquids can be described first by connecting the two instances of isocratic elution. Furthermore, multiple mobile phases can be used in succession. In the case of gradient elution, from the same perspective, infinitesimal time intervals may be integrated by perfoiming successive instances of stepwise elution.
[0261] In addition, the van't Hoff's equation for retention coefficient and temperature T [K] is used, and the Andrade's viscosity equation derived from the Arrhenius equation for the relationship between viscosity η and temperature is used. Since viscosity acts on p.sub.η, temperature also affects Π of the present application. In addition, since the van Deemter's equation, which represents H, can be expanded to an expression containing a temperature-dependent diffusion coefficient Dm [m.sup.2/s], the temperature also affects the peak broadening. In D.sub.m, m indicates diffusion in a mobile phase. Dr. Poppe defined Rudest velocity which is the result of division of the product of u.sub.0 and d.sub.P by D.sub.m, but by rewriting the van Deemter's equation using the Rudest velocity, the temperature dependence of the van Deemter's equation can be expressed.
[0262] The IEC is based on equilibrium constants of a filler, solute, and mobile phase of a column, and there is a relational equation of the equilibrium constant and the retention coefficient. Furthermore, it is known that the dissociation properties of the amino acid molecules themselves vary depending on the component type according to the pH of the mobile phase. Cations and zwitterions of each amino acid are also produced on the basis of the equilibrium constants. Even through the zwitterions do not exhibit an ion-exchange phenomenon, the zwitterions may show a phenomenon of distribution to the filler. This distribution phenomenon also has a certain equilibrium constant.
Other Matters
[0263]
[0264] In addition, the liquid chromatographic data processing device as described above is not limited to being configured as a device including the display unit 110 that displays data generated through data processing, and the liquid chromatographic data processing device may be configured as device that outputs data generated by the data processing unit. Specifically, the liquid chromatograph may be an apparatus including, for example, a liquid delivery unit that transmits a mobile phase, a sample injection unit that injects a sample into a flow stream of the transmitted mobile phase, a column that separates the injected sample, a detection unit that detects the analytes separated, a controller that processes the detection results, and a controller that examines and sets operational and measurement conditions of the liquid delivery unit, the column, and the detection unit, and the like.