Quick quantitative analysis method and analyzer for mixture based on spectral information

Abstract

The present invention relates to a quick quantitative analysis method and analyzer for mixture concentration information. A quick quantitative analysis method for a mixture based on spectral information includes: collecting a sample of a mixture solution, and injecting into a DAD to obtain DAD data; then, calculating a spectral library by a quick qualitative analysis method based on a vector error algorithm to obtain a spectral error vector; determining a spectral curve of a component included in the data corresponding to the sample, according to a value of the error vector; and calculating a content flag value of each component in the sample and concentration information of each substance.

Claims

1. A quick quantitative analysis method for a mixture based on spectral information, comprising the following steps: step S1: obtaining diode array detector (DAD) data D by a DAD, wherein the DAD data D are directly output from the DAD to a control circuit; step S2: by the control circuit, calculating a spectral library S=[s.sub.1 s.sub.2 . . . s.sub.n] by a quick qualitative analysis method based on a vector error algorithm to obtain a spectral error vector ε=[ε.sub.1 ε.sub.2 . . . ε.sub.n]; step S3: determining a spectral curve S*=[s.sub.1* s.sub.2* L s.sub.m*] of a component comprised in the data D corresponding to a sample of a mixture solution, by the control circuit, according to a value of the error vector ε=[ε.sub.1 ε.sub.2 . . . ε.sub.m], wherein m<<n; step S4: calculating a content flag value c=[c.sub.1 c.sub.2 . . . c.sub.m] of each component in the sample by the control circuit according to Formula (1); $\begin{array}{cc}\left[\begin{array}{cccc}{c}_1& 0& L& 0\\ 0& c_2& L& 0\\ M& M& O& M\\ 0& 0& L& c_m\end{array}\right]=\mathrm{pinv}\left(P\right)\times D\times \mathrm{pinv}\left(S^{\prime {\star }_T}\right)& \left(1\right)\end{array}$ wherein, P=[p p . . . p], a vector p is the normalization of a contour of the DAD data D on a time axis, that is, a maximum value is 1; S′*.sup.T is a transpose of S′*, S′*=[s′.sub.1* s′.sub.2* L s′.sub.m*]; a vector s.sub.i′* is the normalization of a vector s.sub.i*; pinv(⋅) is a pseudo-inverse matrix; and step S5: calculating concentration information c.sub.i*, (i=1, 2, L, n) of each substance by using c.sub.i, (i=1, 2, L, m) in Formula (1) by the control circuit according to Formula (2): $\begin{array}{cc}{c}_i^{\star }=\frac{a\times c_i}{{\eta }_i\times b}={\alpha }_i\times c_i& \left(2\right)\end{array}$ wherein, a is an absorbance of the DAD data; b is a thickness of the solution; η.sub.i is a molar absorptivity of an i-th substance; the coefficients a and b are inherent to the instrument; the coefficient η.sub.i depends on a type of the substance, so the coefficient α.sub.i, in Formula (2) depends only on a property of the substance itself.

2. A quick quantitative analyzer for a mixture based on spectral information comprising a liquid circuit system, a DAD and a control circuit, wherein the liquid circuit system is composed of a cleaning liquid pool (12), a sample pool (16), a detection tube (29) and a waste liquid pool (26); the liquid circuit system is interconnected through a flexible liquid tube (14) and an auxiliary gas circuit (15); a connection line between an outlet of the sample pool (16) and the waste liquid pool (26) is sequentially provided with a sample introduction solenoid valve (19), the detection tube (29), a liquid injection solenoid valve (23), a gas-liquid pump (24) and a waste liquid solenoid valve (25); the liquid injection solenoid valve (23) and the waste liquid solenoid valve (25) are used to control a flow direction of gas and liquid circuits; the gas-liquid pump (24) is used to provide power for the entire liquid circuit system; photoelectric pair tubes (20, 22) are respectively installed on upstream and downstream sides of the detection tube (29); a light source (21) and a spectral sensor (30) are oppositely installed on upper and lower sides of the detection tube (29); an output signal of the photoelectric pair tubes and an output signal of the spectral sensor (30) are respectively connected to the control circuit; the control circuit controls and connects each solenoid valve, the light source and the gas-liquid pump (24); wherein the DAD is configured to obtain DAD data D and directly output the DAD data D to the control circuit; and the control circuit is configured to: calculate a spectral library S=[s.sub.1 s.sub.2 . . . s.sub.n] by a quick qualitative analysis method based on a vector error algorithm to obtain a spectral error vector ε=[ε.sub.1 ε.sub.2 . . . ε.sub.n]; determine a spectral curve S*=[s.sub.1* s.sub.2* L s.sub.m*] of a component comprised in the data D corresponding to a sample of mixture solution, according to a value of the error vector ε=[ε.sub.1 ε.sub.2 . . . ε.sub.m], wherein m<<n; calculate a content flag value c=[c.sub.1 c.sub.2 . . . c.sub.m] of each component in the sample according to Formula (1); $\begin{array}{cc}\left[\begin{array}{cccc}{c}_1& 0& L& 0\\ 0& c_2& L& 0\\ M& M& O& M\\ 0& 0& L& c_m\end{array}\right]=\mathrm{pinv}\left(P\right)\times D\times \mathrm{pinv}\left(S^{\prime {\star }_T}\right)& \left(1\right)\end{array}$ wherein, P=[p p . . . p], a vector p is the normalization of a contour of the DAD data D on a time axis, that is, a maximum value is 1; S′*.sup.T is a transpose of S′*, S′*=[s′.sub.1* s′.sub.2* L s′.sub.m*]; a vector s.sub.i′* is the normalization of a vector s.sub.i* ; pinv(⋅) is a pseudo-inverse matrix; and calculate concentration information c.sub.i*, (i=1, 2, L, n) of each substance by using c.sub.i, (i=1, 2, L, m) in Formula (1) according to Formula (2): $\begin{array}{cc}{c}_i^{\star }=\frac{a\times c_i}{{\eta }_i\times b}={\alpha }_i\times c_i& \left(2\right)\end{array}$ wherein, a is an absorbance of the DAD data; b is a thickness of the solution; η.sub.i is a molar absorptivity of an i-th substance; the coefficients a and b are inherent to the instrument the coefficient η.sub.i depends on a type of the substance, so the coefficient a, in Formula (2) depends only on a property of the substance itself.

3. The quick quantitative analyzer for a mixture based on spectral information according to claim 2, wherein a communication line between the cleaning liquid pool (12) and the sample pool (16) is provided with a cleaning solenoid valve (13); a middle part of the sample pool (16) is provided with a sealing slider (17) for intercepting a gas circuit from a sample injection port (6); a self-reset button (18) is installed below the sample pool (16), and a button (5) is installed above the sample pool (16); the self-reset button (18) and the button (5) are connected to the control circuit.

4. The quick quantitative analyzer for a mixture based on spectral information according to claim 3, wherein the cleaning liquid pool (12) is provided with a high liquid level sensor (11) and a low liquid level sensor (10), and the control circuit obtains capacity information of a cleaning liquid through the liquid level sensors; the waste liquid pool (26) is provided with a high liquid level sensor (27) and a low liquid level sensor (28), and the control circuit obtains capacity information of a waste liquid through the liquid level sensors.

5. The quick quantitative analyzer for a mixture based on spectral information according to claim 4, wherein an upper part of the waste liquid pool (26) is provided with a vent hole 8 to facilitate the liquid circuit system to form a gas circulation path; a lower part of the waste liquid pool (26) reserves a drain port (7) to facilitate the discharge of the waste liquid.

6. The quick quantitative analyzer for a mixture based on spectral information according to claim 2, wherein the cleaning liquid pool (12) is provided with a high liquid level sensor (11) and a low liquid level sensor (10), and the control circuit obtains capacity information of a cleaning liquid through the liquid level sensors; the waste liquid pool (26) is provided with a high liquid level sensor (27) and a low liquid level sensor (28), and the control circuit obtains capacity information of a waste liquid through the liquid level sensors.

7. The quick quantitative analyzer for a mixture based on spectral information according to claim 6, wherein an upper part of the waste liquid pool (26) is provided with a vent hole (8) to facilitate the liquid circuit system to form a gas circulation path; a lower part of the waste liquid pool (26) reserves a drain port (7) to facilitate the discharge of the waste liquid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram showing a working principle of high performance liquid chromatography-diode array detector (HPLC-DAD) and a design scheme of the present invention;

(2) FIG. 2 is an external view of a quick quantitative analyzer for a mixture according to the present invention;

(3) FIG. 3 is a schematic structural diagram of a quick quantitative analyzer for a mixture according to the present invention;

(4) FIG. 4 is a schematic diagram of a liquid circuit system of a quick quantitative analyzer for a mixture according to the present invention; and

(5) FIG. 5 is a schematic diagram of a quick quantitative analysis method according to the present invention.

DETAILED DESCRIPTION

(6) The present invention is described in more detail below with reference to specific implementations. The following embodiments are merely intended to illustrate the present invention, rather than to limit the protection scope of the present invention. Those skilled in the art may make replacements and simple combinations with conventional technical means without departing from the protection scope of the present invention.

Embodiment 1

(7) The present invention provides a quick quantitative analysis method for a mixture based on spectral information, as shown in FIG. 5, including the following steps:

(8) step S1: collect a sample of a mixture solution, inject into a DAD so that the detector gives DAD data D;

(9) step S2: calculate a spectral library S=[s.sub.1 s.sub.2 . . . s.sub.n] by a quick qualitative analysis method based on a vector error algorithm to obtain a spectral error vector ε=[ε.sub.1 ε.sub.2 . . . ε.sub.n];

(10) step S3: determine a spectral curve S*[=s.sub.1* s.sub.2* L s*.sub.m] of a component included in the data D corresponding to the sample, according to a value of the error vector ε=[ε.sub.1 ε.sub.2 . . . ε.sub.m], where m<<n;

(11) step S4: calculate a content flag value c=[c.sub.1 c.sub.2 . . . c.sub.m] of each component in the sample according to Formula (1):

(12) $\begin{array}{cc}\left[\begin{array}{cccc}{c}_1& 0& L& 0\\ 0& c_2& L& 0\\ M& M& O& M\\ 0& 0& L& c_m\end{array}\right]=\mathrm{pinv}\left(P\right)\times D\times \mathrm{pinv}\left(S^{\prime *T}\right)& \left(1\right)\end{array}$

(13) where, P=[p p . . . p], a vector p is the normalization of a contour of the DAD data D on a time axis, that is, a maximum value is 1; S′*.sup.T is a transpose of S′*, S′*=[s′.sub.1* s′.sub.2* L s′.sub.m*]; a vector s′.sub.i* is the normalization of a vector s.sub.i*; pinv(⋅) is a pseudo-inverse matrix;

(14) step S5: calculating concentration information c.sub.i*, (i=1, 2, L, n) of each substance by using c.sub.i, (i=1, 2, L, m) in Formula (1) according to Formula (2):

(15) $\begin{array}{cc}{c}_i^{*}=\frac{a\times c_i}{{\eta }_i\times b}={\alpha }_i\times c_i& \left(2\right)\end{array}$

(16) where, a is an absorbance of the DAD data; b is a thickness of the solution; m is a molar absorptivity of an i-th substance; the coefficients a and b are inherent to the instrument; the coefficient η.sub.i depends on a type of the substance (i.e. qualitative information), so the coefficient α.sub.i in Formula (2) depends only on a property of the substance itself.

(17) In the present invention, the quantitative analysis method for a mixture based on spectral information uses the DAD to generate/obtain the DAD data automatically. The method performs the analysis and calculation based on formulas (1) and (2) to finally obtain the concentration information of each substance. In this process, the qualitative calculation is solved by a previously proposed patent, while the quantitative calculation is solved by the present patent. The quantitative calculation is solved based on the qualitative calculation.

Embodiment 2

(18) Referring to FIG. 3 and FIG. 4, this embodiment provides a quick quantitative analyzer for a mixture based on spectral information, for implementing the above quick quantitative analysis method for a mixture, including a liquid circuit system, a DAD and a control circuit. The liquid circuit system is composed of a cleaning liquid pool 12, a sample pool 16, a detection tube 29 and a waste liquid pool 26. The liquid circuit system is interconnected through a flexible liquid tube 14 and an auxiliary gas path 15. A connection line between an outlet of the sample pool 16 and the waste liquid pool 26 is sequentially provided with a sample introduction solenoid valve 19, the detection tube 29, a liquid injection solenoid valve 23, a gas-liquid pump 24 and a waste liquid solenoid valve 25. The liquid injection solenoid valve 23 and the waste liquid solenoid valve 25 are used to control a flow direction of gas and liquid circuits. The gas-liquid pump 24 is used to provide power for the entire liquid circuit system. Photoelectric pair tubes are respectively installed on upstream and downstream sides of the detection tube 29. A light source 21 and a spectral sensor 30 (i.e. the DAD) are oppositely installed on upper and lower sides of the detection tube 29. An output signal of the photoelectric pair tubes and an output signal of the spectral sensor 30 are respectively connected to the control circuit. The control circuit controls and connects each solenoid valve, the light source and the gas-liquid pump 24.

(19) The photoelectric pair tube 20 is installed on a left side of the detection tube 29 to obtain a signal of a sample flowing into the detection tube 29. The photoelectric pair tube 22 is installed on a right side of the detection tube 29 to obtain a signal of the sample flowing out of the detection tube 29. The control circuit completes coordinated control between the various components. When the sample flows through the detection tube 29, the control circuit controls the light source 21 to turn on, and reads acquired DAD data from the spectral sensor 30. After passing through the detection tube 29, the sample directly flows into the waste liquid pool 26 for temporary storage.

(20) The spectral sensor 30, i.e. the DAD, uses a standard interface module to directly input the DAD data to the control circuit for calculation and analysis.

Embodiment 3

(21) Referring to FIG. 3 and FIG. 4, this embodiment provides a quick quantitative analyzer for a mixture based on spectral information. This embodiment is different from Embodiment 1 in that: further, a communication line between the cleaning liquid pool 12 and the sample pool 16 is provided with a cleaning solenoid valve 13; a middle part of the sample pool 16 is provided with a sealing slider 17 for intercepting a gas circuit from a sample injection port 6; a self-reset button 18 is installed below the sample pool 16, and a button 5 is installed above the sample pool 16; the self-reset button 18 and the button 5 are connected to the control circuit.

(22) The components of the gas and liquid circuits are connected through a flexible liquid tube. The use of the flexible liquid tube is convenient for installation and convenient for the flexible installation of the sample pool. A user can touch the sample pool through the button 5, thereby triggering the button 18 to generate a button signal to notify the control circuit.

(23) In the quick quantitative analyzer for a mixture based on spectral information, the cleaning liquid pool 12 is provided with a high liquid level sensor 11 and a low liquid level sensor 10, and the control circuit obtains capacity information of a cleaning liquid through the liquid level sensors; the waste liquid pool 26 is provided with a high liquid level sensor 27 and a low liquid level sensor 28, and the control circuit obtains capacity information of a waste liquid through the liquid level sensors. An upper part of the waste liquid pool 26 is provided with a vent hole 8 to facilitate the liquid circuit system to form a gas circulation path; a lower part of the waste liquid pool 26 reserves a drain port 7 to facilitate the discharge of the waste liquid.

Embodiment 4

(24) The present invention provides a quick quantitative analysis analyzer for a mixture based on spectral information, having an appearance as shown in FIG. 2. A housing 1 of the entire analyzer is composed of a cube. The entire analyzer outputs voice status information through a speaker 2. The user can use a mobile phone to scan a quick response code 3 to download a mobile application (APP). The analyzer feeds back optical status information (see Table 1 for a specific status) of the analyzer to the user through a two-color (white and red) light-emitting diode (LED) ring 4. The user can realize start-up, shutdown and necessary user input through the button 5 (a function of the button 5 is shown in Table 2). The user injects a sample to be detected into the analyzer through the sample injection port 6. When the waste liquid in the analyzer reaches a certain amount, the user can discharge the waste liquid through the drain port 7. In a laboratory environment, the user can also install a drain pipe at the drain port 7 to directly discharge the waste liquid each time an experiment is performed.

(25) TABLE-US-00001 TABLE 1 LED status and description SN LED Status Description of Status 1 White flashes slowly The system is self-testing. 2 White The analyzer passes steady on the self-test and is idle. 3 White flashes quickly The analyzer is in an analysis mode. 4 Red flashes The analyzer fails the slowly self-test and issues a voice prompt through a voice module to a part that fails the self-test. 5 Red The analyzer malfunctions steady on during operation and issues a voice prompt through the voice module. 6 Red flashes The waste liquid pool is full, quickly and a voice prompt is issued through the voice module. 7 Yellow Low (red and white on battery at the same time)

(26) TABLE-US-00002 TABLE 2 Description of button functions SN LED Status Description of Status 1 Click under a The system is powered on shutdown state and enters self-test. 2 Click with A sample detection function is started, white and a voice prompt is continuously light on issued through the voice module. 3 Double-click The analyzer starts to connect a with white network and issues a voice prompt light on through the voice module. Now, the user needs to set a network parameter of the analyzer through the APP on the mobile phone. 4 Long press with If the system is currently idle, it will white shut down directly; if it is light on currently in a sample detection state, it will shut down after completing the current operation; if it is currently in a cleaning liquid filling state, it will stop filling and issue a voice prompt, and then shut down. 5 Click while red The analyzer flashes slowly retests itself. 6 Click while The analyzer reports an error type and red steady on a corrective action through the voice module. 7 Click while If the system is currently idle, it will yellow shut down directly; if it is currently steady on in a sample detection state, it will shut down after completing the current operation; if it is currently in a cleaning liquid filling state, it will stop filling and issue a voice prompt, and then shut down.

(27) FIG. 3 and FIG. 4 show an internal structure of the quick quantitative analyzer. A cleaning liquid pool 12, a sample pool 16, a detection tube 29 and a waste liquid pool 26 compose a liquid circuit system of the analyzer. The liquid circuit system is interconnected through a flexible liquid tube 14 and an auxiliary gas circuit 15. A cleaning solenoid valve 13, a sample introduction solenoid valve 19, a liquid injection solenoid valve 23 and a waste liquid solenoid valve 25 are used to control a flow direction of gas and liquid circuits. A gas-liquid pump 24 is used to provide power for the entire liquid circuit system. The cleaning liquid pool 12 stores a cleaning liquid for cleaning the entire liquid system to wait for a next detection. The sample to be detected is injected into the sample pool 16 through the sample injection port 6 and waits for detecting there. When the sample flows through the detection tube 29, a control circuit controls a light source 21 to turn on, and reads acquired DAD data from a spectral sensor 30. After passing through the detection tube 29, the sample directly flows into the waste liquid pool 26 for temporary storage. An upper part of the waste liquid pool 26 is provided with a vent hole 8 to facilitate the liquid circuit system to form a gas circulation path; a lower part of the waste liquid pool 26 reserves a drain port 7 to facilitate the discharge of the waste liquid.

(28) The cleaning liquid pool 12 is provided with a high liquid level sensor 11 and a low liquid level sensor 10 for providing capacity information of the cleaning liquid. The waste liquid pool 26 is provided with a high liquid level sensor 27 and a low liquid level sensor 28 for providing capacity information of the waste liquid. A middle part of the sample pool 16 is provided with a sealing slider 17 for intercepting a gas circuit from the sample injection port 6. A photoelectric pair tube 20 is installed on a left side of the detection tube 29 to obtain a signal of the sample flowing into the detection tube 29. A photoelectric pair tube 22 is installed on a right side of the detection tube 29 to obtain a signal of the sample flowing out of the detection tube 29. The control circuit completes coordinated control between the various components. The voice module outputs voice prompt information. A communication module realizes Bluetooth and WiFi communication. A battery 9 powers the entire analyzer.

(29) The main workflow of the analyzer includes: sample detection, liquid circuit cleaning, and filling with the cleaning liquid. These processes are described in detail below with reference to FIG. 3 and FIG. 4.

(30) (1) Sample detection. When the analyzer is idle, the cleaning solenoid valve 13 and the sample introduction solenoid valve 19 are closed. A lower side line of the three-way liquid injection solenoid valve 23 is opened, and an upper side line is closed; a right side line of the three-way waste liquid solenoid valve 25 is opened, and a left side line is closed. When the white LED light steady on, the user injects the sample to be detected into the sample pool 16 through the sample injection port 6. The user clicks the button 5 to start sample detection. The control circuit activates the gas-liquid pump 24 and opens the sample introduction solenoid valve 19. The sample flows in the liquid circuit system at a certain rate. When the sample passes through the photoelectric pair tube 20, the control circuit turns on the light source 21 and drives the spectral sensor 30 to acquire data. After the sample totally passes through the photoelectric pair tube 22, the control circuit turns off the light source 21 and the spectral sensor 30. The gas-liquid pump 24 continues to work for 10 s, so that the sample flows into the waste liquid pool 26.

(31) (2) Liquid circuit cleaning. The liquid circuit needs to be cleaned each time after a sample is detected. When the liquid circuit is cleaned, the control circuit drives the sealing slider 17 to intercept the gas circuit from the sample injection port 6. Then the cleaning solenoid valve 13 and the sample introduction solenoid valve 19 are opened. The lower side line of the three-way liquid injection solenoid valve 23 is opened, and the upper side line is closed; the right side line of the three-way waste liquid solenoid valve 25 is opened, and the left side line is closed. At the same time, the gas-liquid pump is started to work. Thus, the atmospheric pressure passes through the auxiliary gas circuit 15 to push the cleaning liquid into the gas and liquid circuits to complete the cleaning work of the gas and liquid circuits.

(32) (3) Filling with the cleaning liquid. The filling process of the cleaning liquid needs to be started through the mobile phone APP. The principle is shown in FIG. 4. The cleaning liquid is stored in a container 35. A manual valve 34 is installed at a lower left side of the container to control the outflow of the cleaning liquid. The valve 34 is connected to a liquid injection probe 32 through a flexible hose 33. A lower end of the injection probe 32 is provided with a sealing gasket. The container 35 is kept higher than the sample injection port 6 when the liquid is injected. Then the liquid injection probe 32 is inserted into the sample pool 16 to be lower than the auxiliary gas circuit 15. The control circuit opens the cleaning solenoid valve 13 and the sample introduction solenoid valve 19. The upper side line of the three-way liquid injection solenoid valve 23 is opened, and the lower side line is closed; the left side line of the three-way waste liquid solenoid valve 25 is opened, and the right side line is closed. At this time, a gas path is formed from the vent hole 8 to the left side line of the waste liquid solenoid valve 25, to the upper side line of the liquid injection solenoid valve 23, to the sample introduction solenoid valve 19, to the cleaning solenoid valve 13, and to the auxiliary gas circuit 15. The control circuit activates the gas-liquid pump 24 and opens the valve 34. The cleaning liquid is injected into the cleaning liquid pool 12 from the above-mentioned gas path. When the upper liquid level sensor 11 receives a signal, the gas-liquid pump is stopped, and the cleaning solenoid valve 13 and the sample introduction solenoid valve 19 are closed, thereby completing the filling of the cleaning liquid.

(33) FIG. 5 shows a principle of a quick quantitative analysis method. D is DAD data obtained by the above-mentioned analyzer. s.sub.i, (i=1, 2, L, n) is a spectral curve in a standard spectral library. A qualitative recognition method (content of a different patent) calculates an error of each spectral curve in the DAD data D to obtain an error ε.sub.i, (i=1, 2, . . . , n). Each spectral curve exists in the DAD data D is determined according to the error of the spectral curve.

(34) As shown in FIG. 5, if it is determined that s.sub.i*, (i=1, 2, L, m) exists in the DAD data D, a content flag value c.sub.i, (i=1, 2, L, m) of each substance is calculated according to a quantitative algorithm shown in Formula (1).

(35) $\begin{array}{cc}\left[\begin{array}{cccc}{c}_1& 0& L& 0\\ 0& c_2& L& 0\\ M& M& O& M\\ 0& 0& L& c_m\end{array}\right]=\mathrm{pinv}\left(P\right)\times D\times \mathrm{pinv}\left(S^{\prime *T}\right)& \left(1\right)\end{array}$

(36) where, P=[p p . . . p], a vector p is the normalization of a contour of the DAD data D on a time axis, that is, a maximum value is 1; S′*.sup.T is a transpose of S′*, S′*=[s′.sub.1* s′.sub.2* L s′.sub.m*]; a vector s′.sub.i* is the normalization of a vector s.sub.i*; pinv(⋅) is a pseudo-inverse matrix; concentration information c.sub.i*, (i=1, 2, L, m) of each substance is calculated by using c.sub.i, (i=1, 2, L, m) in Formula (1) according to Formula (2):

(37) $\begin{array}{cc}{c}_i^{*}=\frac{a\times c_i}{{\eta }_i\times b}={\alpha }_i\times c_i& \left(2\right)\end{array}$

(38) In the formula, a is an absorbance of the DAD data; b is a thickness of the solution; m is a molar absorptivity of an i-th substance. The coefficients a and b are inherent to the instrument; the coefficient m depends on a type of the substance (i.e. qualitative information). Therefore, the coefficient α.sub.i in Formula (2) depends only on a property of the substance itself