Abstract
A fluidic system for fraction collection comprises a switching valve having a plurality of ports for connecting first and second ports in different configurations. An inlet line is directly connected to the first port, and a collection device is directly connected to the second port. In a collection configuration, the first port and the second port are connected. The ports further comprise third and fourth ports, and the fluidic system further comprises a buffer section directly connected to the third and fourth ports. The fluidic system further comprises a first collection reservoir and is configured to position the collection device to expel a fluid into the first collection reservoir. In a buffer configuration, fluid flows through the inlet line, the first port, the third port, the buffer section, the fourth port, the second port, and the collection device.
Claims
1. A fluidic system, comprising: a switching valve comprising a plurality of ports, wherein the switching valve is configured for connecting the ports in different configurations, wherein the ports comprise a first port and a second port; an inlet line directly connected to the first port; and a collection device directly connected to the second port, wherein the fluidic system is configured to assume a collection configuration, wherein the first port and the second port are connected, wherein the ports comprise a third port and a fourth port, wherein the fluidic system comprises a buffer section directly connected to the third port and the fourth port, and wherein the fluidic system is configured to assume a buffer configuration, wherein the first port and the third port are connected and the fourth port and the second port are connected.
2. The fluidic system according to claim 1, wherein the ports comprise a pump port directly connected to a pump and a waste port directly connected to waste, and wherein the fluidic system is configured to assume a buffer section wash configuration, wherein the pump port and the fourth port are connected and the third port and the waste port are connected.
3. The fluidic system according to claim 1, wherein the switching valve comprises a first connecting element for connecting the ports.
4. The fluidic system according to claim 3, wherein the first connecting element connects the first port and the second port in the collection configuration.
5. The fluidic system according to claim 1, wherein the fluidic system comprises a first collection reservoir, and wherein the fluidic system is configured to position the collection device to expel a fluid into the first collection reservoir.
6. The fluidic system according to claim 1, further comprising a second collection reservoir, and wherein the fluidic system is configured to position the collection device to expel a fluid into the second collection reservoir.
7. The fluid system according to claim 1, wherein: the ports comprise a discharge port, the switching valve comprises a stator, wherein the stator comprises the plurality of ports, wherein the switching valve comprises a rotor, wherein the rotor comprises at least one connecting element for connecting the ports in the different configurations, wherein the at least one connecting element is at least one groove, wherein the rotor comprises a groove connected to the second port and extending between the second port and the discharge port, wherein the switching valve is configured to assume a collection configuration fluidly connecting the first port and the second port, wherein the switching valve is configured to assume a discharge configuration fluidly connecting the first port and the discharge port, and wherein the switching valve is configured to transition from the collection configuration to the discharge configuration such that the first port is always connected to the second port or the discharge port during the transition.
8. A method of operating a fluidic system having: a switching valve comprising a plurality of ports, wherein the switching valve is configured for connecting the ports in different configurations, wherein the ports comprise a first port and a second port, an inlet line directly connected to the first port, a collection device directly connected to the second port, and wherein the fluidic system is configured to assume a collection configuration, wherein the first port and the second port are connected, wherein the ports comprise a third port and a fourth port, wherein the fluidic system comprises a buffer section directly connected to the third port and the fourth port, wherein the fluidic system is configured to assume a buffer configuration, wherein the first port and the third port are connected and the fourth port and the second port are connected, wherein the method comprises: with the fluidic system assuming the collection configuration, causing a fluid flow through the inlet line, the first port, the second port, and the collection device into a first collection reservoir.
9. The method of claim 8, further comprising: with the fluidic system assuming the buffer configuration, causing a second fluid flow flowing through the inlet line, the first port, the third port, the buffer section, the fourth port, the second port, and the collection device.
10. The method of claim 9, wherein the second fluid flow causes fluid to flow into the first collection reservoir.
11. The method of claim 9, wherein the ports of the fluidic system comprise a pump port directly connected to a pump and a waste port directly connected to waste and the fluidic system is configured to assume a buffer section wash configuration, wherein the pump port and the fourth port are connected and the third port and the waste port are connected, the method further comprising: with the fluidic system assuming the buffer section wash configuration after the fluidic system assumes the buffer configuration, causing a washing flow through the pump port, the fourth port, the buffer section, the third port, the waste port, and towards the waste.
12. The method of claim 11, wherein the fluidic system includes a second collection reservoir, and the fluidic system is configured to position the collection device to expel a fluid into the second collection reservoir, the method further comprising: with the fluidic system again assuming the collection configuration after the fluidic system assumes the buffer section wash configuration, causing a fluid flow through the inlet line, the first port, the second port, and the collection device into the second collection reservoir.
13. A computer program product comprising instructions configured to, when run on a control unit of the fluidic system, cause the fluidic system to perform the method of claim 8.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0208] FIG. 1 depicts a fluidic system in an idle state;
[0209] FIG. 2 includes FIGS. 2a-2d and depicts a switching valve configured to be used in the fluidic system;
[0210] FIG. 3 depicts the fluidic system in a discharge configuration where eluates are being directed towards a waste reservoir;
[0211] FIG. 4 depicts the fluidic system in a collection configuration where eluates are being collected in a collection reservoir;
[0212] FIG. 5 depicts the fluidic system in a buffer configuration where a buffer section is brought into the fluid flow path;
[0213] FIG. 6a depicts a solvent being drawn in by a pump in the fluidic system;
[0214] FIG. 6b depicts a preparation step of the fluidic system to prepare it for collection of a first fraction;
[0215] FIG. 7a depicts arrival of the first fraction into a detector upstream of the fluidic system;
[0216] FIG. 7b depicts collection of the first fraction into a first collection reservoir using the fluidic system;
[0217] FIG. 8a depicts arrival of a second fraction into the detector;
[0218] FIG. 8b depicts the fluidic system in the buffer configuration with the first fraction now being pushed through the buffer section before collection;
[0219] FIG. 9 depicts a washing of the buffer section to prepare it for subsequent collections;
[0220] FIG. 10 depicts the collection of the second fraction into a second collection reservoir;
[0221] FIG. 11 depicts the switching of the fluidic system between collection of two fractions without using the buffer section; and
[0222] FIG. 12 depicts the collection of a second fraction without using a buffer section earlier;
[0223] FIG. 13 includes FIGS. 13a-13b and depicts ports and connecting elements on the switching valve;
[0224] FIG. 14 includes FIGS. 14a-14c and depicts fluidic connections as the switching valve is switched between the collection and discharge configurations; and
[0225] FIG. 15 includes FIGS. 15a-15c and depicts fluidic connections as the switching valve is switched between the discharge and buffer configurations.
DETAILED DESCRIPTION
[0226] FIG. 1 depicts one embodiment of a fluidic system 10, that may be a liquid chromatography system, preferably an HPLC system, that may be used to collect fractions eluted downstream of a detector 900. The detector 900 may be a UV detector, that may detect presence of components in the fluid flowing through it based on an absorption of light by the components in the fluid, or it may be another non-destructive detector, e.g., another optical detector. It will be understood that the fluidic system 10 may be configured to be used together with other components of the HPLC system, that may comprise at least a separation column 860 upstream of the detector 900, a sample storage section, e.g., a sample loop 870 upstream of the separation column 860 and an analytical pump 850 driving the mixture of a solvent and sample from the storage section 870 through the separation column 860. Furthermore, the system may also comprise a unit 880 for introducing a sample into a system, e.g., a metering device 880 connected to a needle 890, which may be connected to a needle seat 895. While these components are only depicted in FIG. 1 for sake of simplicity of the illustrations, those skilled in the art will understand that such components may also be present in the configurations depicted in the other Figures.
[0227] The fluidic system 10, that may also be referred to as a fraction collector, may further comprise a rotary valve 200 (that may be called a fraction or switching valve) that comprises a plurality of ports (0 to 8, where the first port 0 is directly connected to the detector 900 via an inlet line and carries the mixture eluted from the separation column) and a plurality of connecting elements 210, that may be called the first connecting element 210b, the second connecting element 210a, and the third connecting element 210c. Each of the connecting elements 210 is configured to changeably connect the plurality of ports of the valve 200. The system 10 further comprises a waste reservoir 700 directly connected to a discharge port 3 and a waste port 5 of the valve. The system 10 may also comprise a pump 100 (that may be a flush pump, or a container with pressurized gas, or a metering device) directly connected to a pump port 8, and a collection device 300, that may comprise a collection tube 320 and a collection needle 310. The collection device 300 may be directly connected to the second port 2. The pump 100 may be configured to provide an operating pressure of 8 bar, for example. It may further comprise an internal cavity that may store the cleaning/wash solvent. The volume of the internal cavity may, for example, be 1 ml. The depicted system 10 further comprises a wash section 600 that may be used to wash the collection needle 310, and a buffer section 400, that may be a buffer ring, directly connected to the third port 4 and to the fourth port 1 of the switching valve 200.
[0228] When a component is said to be directly connected to a port of the switching valve 200, this should denote a fluid connection between the component and the respective port of the switching valve 200, without there being another port present in the connection between the component and the respective port. For example, in the configuration depicted in FIG. 1, the detector 900 is directly connected to the first port 0. These two elements are connected to one another and there is no other port present in this connection. Further, in FIG. 1, the detector 900 is also connected to the port 3, which may be referred to as discharge port 3. However, the connection between the detector 900 and the discharge port 3 is via the first port 0. That is, there is another port of the valve 200 present in this connection, such that this connection is not a direct connection as used in the present specification.
[0229] With further regard to the Figures, it is noted that in the depicted Figures, no port 6 is depicted. Thus, whenever mention is made of ports 0 to 8, it may be understood that the port 6 is absent from the switching valve. Alternatively, it may be present on the switching valve but may not be involved in carrying out the method described below.
[0230] The fluidic system 10 further comprises a plurality of collection reservoirs 500 (500a, 500b, 500c), which may also be referred to as vials, that may be used to collect a plurality of fractions eluted from a separation column upstream of the detector 900, and a solvent reservoir 50 that may comprise a solvent that may be used for washing the fluidics in the fluidic system 10, such as the buffer section 400 or the collection device 300. The collection needle 310 may be configured to be moved into one of the plurality of collection reservoirs 500 when needed. In embodiments, the collection reservoirs 500 may be arranged in a 1-dimensional or 2-dimensional array and the motion of the collection needle 310 may be appropriately configured. The solvent reservoir 50 may be further connected directly to the wash section 600 to provide a wash solvent for washing the outer surface of the connection needle 310. That is, in the example depicted in FIG. 1, the same solvent is used to wash both the buffer section 400 and the outer surface of the connection needle 310. However, this is merely exemplary and different solvents may be provided in different solvent reservoirs 50 to wash the buffer section 400 and the outer surface of the connection needle 310. In this case, there may be different solvent reservoirs, one connected to the port 7 and another one being connected to wash section 600.
[0231] The fluidic system 10 may further comprise at least one flow sensor 800 (or a plurality of flow sensors). At least one of these flow sensors 800 may be installed on the waste line, i.e., upstream of the waste reservoir 700 and configured to measure a flow rate of fluid that flows into the waste reservoir 700. This may help to determine the time at which a fraction to be collected arrives into the collection needle 310 as follows: a delay volume of the fluidics connecting the outlet of the detector 900 to the collection needle 310 may be determined, e.g., at the start of the separation process. Then, based on the flow rate of fluid being discharged into the waste reservoir 700, the time needed for a peak to travel to the collection needle 310 after being eluted from the detector 900 may be determined, for example. This would then represent an upper limit for the time needed for accurately switching the switching valve 200 and bringing the collection needle 310 to an empty collection reservoir 500, for example, after detecting the peak in the detector 900.
[0232] The fluidic system 10 may further comprise a control unit 60, configured to control the rotation of the rotor based on feedback from the flow sensor 800, where the data connection is depicted as dotted lines. This may allow switching the operating modes of the fluidic system 10 to a suitable mode as described further below.
[0233] The control unit 60, which may also be referred to as controller 60, can be operatively connected to other components, as depicted by dotted lines in FIG. 1. More particularly, the controller 60 may be operatively connected to the valve 200 (and more particularly to rotatable drives thereof), to the sensor 800, to the pump 100, to the metering device 880 (and more particularly to a stepper motor of the metering device 880), and to the collection device 300.
[0234] The controller 60 can include a data processing unit and may be configured to control the system and carry out particular method steps. The controller can send or receive electronic signals for instructions. The controller can also be referred to as a microprocessor. The controller can be contained on an integrated-circuit chip. The controller can include a processor with memory and associated circuits. A microprocessor is a computer processor that incorporates the functions of a central processing unit on a single integrated circuit (IC), or sometimes up to a plurality of integrated circuits, such as 8 integrated circuits. The microprocessor may be a multipurpose, clock driven, register based, digital integrated circuit that accepts binary data as input, processes it according to instructions stored in its memory and provides results (also in binary form) as output. Microprocessors may contain both combinational logic and sequential digital logic. Microprocessors operate on numbers and symbols represented in the binary number system.
[0235] While the controller 60 is only depicted in FIG. 1 (for sake of simplicity), it should be understood that the controller is typically also present when the system assumes the other configurations depicted in the other Figures.
[0236] Additionally, the fluidic system 10 may be further configured to be used together with a computer program product that may comprise instructions for causing the control unit to switch the switching valve 200 and/or to move the collection needle 310 over a designated collection reservoir 500.
[0237] FIG. 1 further depicts a configuration of the fluidic system 10 where the second connecting element 210a connects ports 1 and 8, the first connecting element 210b connects ports 0 and 3, and the third connecting element 210c connects ports 4 and 5. The configuration depicted in FIG. 1 may represent a typical setup in a chromatographic separation process without a fraction collector, wherein fluid is passed into the waste reservoir 700 after being analyzed in the detector 900. In this configuration, no eluates are collected in the collection reservoirs 500. Because the waste reservoir 700 may have been used to collect liquid from prior steps in the separation process, including, for e.g., a step of washing and equilibrating the separation column, the mixture collected in the waste reservoir 700 may not be suitable for a further analysis. Thus, it may be advantageous to provide a separate fraction collection procedure (i.e., a procedure to collect defined fractions of the sample to different reservoirs) if further analysis of the eluted fractions is to be carried out.
[0238] It may also be noted that the flush solvent used to dispense remaining liquid inside the collection device 300 and collection needle 310 depicted in FIG. 1 may be either the mobile phase used in the fluidic system (that may be an HPLC system) flow or it may be an additional wash solvent prepared by a user. The additional cleaning/wash solvent may also be used to fill up the pump 100 before each sample injection.
[0239] Thus, in other words, the fluidic system 10 as depicted in FIG. 1 may comprise a fraction collection system, that may be called a fraction collector. The fluidic system 10 may comprise a multi-port rotary valve, or switching valve 200, that may also be referred to as a fraction valve, a flow sensor 800 (or a plurality of flow sensors) installed on a waste line to the waste reservoir 700, a pump 100, a collection device 300 comprising a collection needle 310 and a collection tube 320 and its wash section 600, and a buffer section 400.
[0240] It is an aim of the present invention to use the additional components as depicted in FIG. 1, namely, the switching valve 200, the buffer section 400, and the collection reservoirs 500, to provide a robust method to collect fractions downstream of the detector 900. Embodiments of the method and how the depicted configuration may be used to collect a plurality of fractions will now be described.
[0241] FIG. 2a depicts an exemplary design of the switching valve 200. It may comprise a static part, that may be called a stator, comprising the plurality of ports 0 to 8 with direct connections to other components of the fluidic system 10 as described above. The plurality of ports 0 to 8 may be positioned on the stator in a circular arrangement as shown in FIG. 2a.
[0242] The switching valve 200 may further comprise a rotating section, that may be called a rotor, that may comprise a plurality of connecting elements 210, for e.g., 3 connecting elements, 210a, 210b, 210c, configured to provide a fluidic connection between ports of the stator that each of them connects. The connecting elements may be positioned on the rotor as shown in FIGS. 2b to 2d, for example. The dashed lines in FIGS. 2b to 2d indicate parts of the switching valve 200 hidden from the view depicted in FIG. 2a, where the rotor is attached underneath the stator.
[0243] The rotor may be configured to be rotated about an axis perpendicular to the plane of the rotor and passing through its center. The angle by which the rotor may be allowed to rotate may be determined by the relative position of the connecting elements 210 and the ports 0 to 8. For example, in the configuration depicted in FIG. 2, the rotor may be configured to rotate by ±45° with respect to a discharge configuration depicted in FIG. 2b, where the second connecting element 210a is shown to connect ports 1 and 8, the first connecting element 210b is shown to connect ports 0 and 3, and the third connecting element 210c is shown to connect ports 4 and 5. Note that this is also the configuration depicted in FIG. 1. The rotation angle may be chosen to be between 10° and 80°, preferably between 20° and 70°, and further preferably between 30° and 60°. A smaller angle of rotation may allow the rotor to be rotated quickly, improving the efficiency of the fractionation process.
[0244] FIG. 2 further depicts two additional configurations of the rotor. FIG. 2c depicts a collection configuration of the rotor, wherein the second connecting element 210a connects ports 7 and 8, the first connecting element 210b connects ports 0 and 2, and the third connecting element 210c connects ports 3 and 4. This configuration may be obtained, for e.g., by rotating the rotor by −45° from the discharge configuration depicted in FIG. 2b.
[0245] A further configuration is depicted in FIG. 2d that may be called a buffer configuration, obtained by rotating the rotor by +45° from the discharge configuration (see FIG. 2b). In this configuration the second connecting element 210a connects ports 1 and 2, the first connecting element 210b connects ports 0 and 4, and the third connecting element 210c connects port 5 to a dead port, i.e., flow into port 5 is stopped.
[0246] In the depicted embodiments, the connecting elements 210a, 210b, and 210c are depicted with particular shapes. With regard to FIG. 1 and FIG. 2, it will be understood that the first port 0 may be in the center of the valve 200 and that the other ports 1 to 8 may be arranged on a ring or circle with an identical distance to the central port 0. The first connecting element 210b may be generally configured to connect the central port 0 with one of the circumferential ports 1 to 3, and the second and third connecting elements 210a, 210c are configured to connect two of the circumferential ports 1 to 8.
[0247] In the depicted embodiment, the first connecting element 210b is depicted to be hook shaped. That is, it comprises a straight section and an arcuate section. However, it will be understood that this is only one example and that the first connecting element may also be realized in other manners, e.g., it may only comprise a straight section.
[0248] Furthermore, the second and third connecting elements 210a, 210c, are depicted to be arcuate. Again, it should be understood that this is merely exemplary and that they may also be shaped differently (e.g., they may be straight).
[0249] Furthermore, as depicted in the Figures, the circumferential ports 1 to 7 may preferably be located at equal distances to one another (with the exception of ports 5 and 7). Further still, as depicted, e.g., in FIG. 1, the connecting elements 210 may establish the connections between the respective ports without dead volume. See, e.g., the connecting elements 210b connecting the ports 0 and 3 without a dead volume and the connecting element 210c connecting the ports 4 and 5 without a dead volume. Furthermore (although not depicted in FIG. 1), this is also possible for connecting element 210a, which may also be dimensioned in such a way to allow for a dead volume free connection of the respective ports.
[0250] In other words, the switching valve 200 described above may be employed in a fluidic system 10 for fraction collection. It may be embedded inside an HPLC system, for example, to divert HPLC system flow into a waste reservoir 700, collection reservoirs 500, or a buffer section 400 (while the fluidic system 10 is still connected to the collection reservoirs 500) by switching at high speeds over the three work configurations/positions described above: a discharge configuration (FIG. 2b) (that may also be called a waste position), a collection configuration (FIG. 2c), and a buffer configuration (FIG. 2d) (that may also be called a flush position). Use of the buffer section 400 may thus enable an additional ‘flush’ step to be realized with the switching valve 200 as part of the fluidic system 10 as described above. The discharge configuration may be preferably located between the collection configuration and the buffer configuration. This may help to reduce carry-over. The placement of the switching valve 200 in the fluidic system 10 for these configurations is also depicted in FIG. 3 (discharge configuration), FIG. 4 (collection configuration), and FIG. 5 (buffer configuration).
[0251] FIG. 3 depicts a configuration of the fluidic system 10 where the switching valve 200 is in the discharge configuration described above. When comparing FIG. 3 to FIG. 1, the skilled person will understand that in FIG. 1, the port 5 is connected to the waste 700 to which also the port 3 is connected, while FIG. 3 depicts port 5 being connected to a waste 700, which is different from the waste 700 to which port 3 is connected. However, it should be understood that this is interchangeable, i.e., that also in FIG. 3, the port 5 could be connected to the waste 700 to which port 3 is connected (and the same also applies to the subsequent Figures). Furthermore, for sake of simplicity, the connection between the solvent reservoir 50 and the wash port 600 is depicted in a simplified manner in FIG. 3 and the subsequent Figures. As is depicted, e.g., in FIG. 3, the port 5 is connected to the waste 700. However, the line downstream of port 5 also has a junction upstream of the waste reservoir 700. Thus, the port 5 can not only be connected to the waste reservoir 700, but also to the wash port 600 (e.g., by means of a two way valve).
[0252] In this configuration, eluates from the detector 900 are discharged into the waste reservoir 700 while the pump 100 may be used to simultaneously fill up the buffer section 400 with a cleaning solvent that may have been drawn up from the solvent reservoir 50 in a previous step. More particularly, the pump 100 may cause a flow through port 8, port 1, buffer section 400, port 4 and port 5 towards the waste reservoir 700. However, as described, there may also be a valve (e.g., a two way valve) in the connection between the port 5 and the waste reservoir 700. By means of this valve, the fluid flow may also be directed towards the wash port 600 and to the waste reservoir which is also connected to port 3. Thus, the solvent flowing through the buffer section 400 may also be used to wash the wash port 600.
[0253] This may allow the buffer section 400 to be prepared for a subsequent step wherein a fraction eluted from the separation column upstream of the detector 900 may be collected into one of the collection reservoirs 500 via the buffer section 400.
[0254] FIG. 4 depicts the fluidic system 10 making use of the collection configuration of the switching valve 200 described above. In this configuration, the collection needle 310 may be moved from the wash section 600 to one of the collection reservoirs 500, for example, 500a, into which a fraction eluted from the separation column may be collected. Note that ports 7 and 8 may also be connected in this configuration which may allow filling up of the pump 100 with solvent from the solvent reservoir 50 after having been emptied, for example into the buffer section 400, in a previous step.
[0255] FIG. 5 depicts the fluidic system 10 employing the buffer configuration of the switching valve 200 described above. This configuration may be employed when the fluidic system 10 is used for collection of fractions that are eluted relatively closely spaced in time. E.g., in order to avoid contamination of a first eluting fraction by the second eluting fraction, the buffer section 400 may be used to include a buffer separating different fractions. As depicted, in the configuration depicted in FIG. 5, the detector 900 is fluidly connected to the port 0, but there is no fluid connection between the detector 900 and the port 5. While this is depicted by the connection from the detector 900 to the port 0 comprising a curved section, those skilled in the art will understand that such a curved section is not a necessity, but that the connection between detector 900 and port 0 on the one hand, and the connection element 210c e the other hand, may also be located in different planes, i.e., these two elements may be offset from one another in the direction perpendicular to the drawing plane.
[0256] A typical workflow employing the fluidic system 10 as described above to collect two fractions will now be described with reference to FIGS. 6 to 12.
[0257] In a first preparation step, that may be carried out before the start of the separation, the fluidic system 10 may be used to wash the buffer section 400 and the collection needle 310 as shown in FIG. 6. The switching valve 200 is rotated to the collection configuration depicted in FIG. 2c. In order to carry out the process of washing, a wash/cleaning solvent is drawn up into the pump 100 as shown in FIG. 6a. Here, the second connecting element 210a connects the ports 7 and 8 which allows for a flow of fluid from the solvent reservoir 50 into the pump 100. The pump 100 may comprise a piston and housing, and drawing the solvent may comprise the piston being actuated to lower the pressure inside the pump 100. This is also depicted in FIG. 6a.
[0258] FIG. 6a further depicts the first connecting element 210b connecting the ports 0 and 2 of the switching valve 200. As a result, fluid ejected from the detector 900 into the inlet line flows into the wash section 600. Since this step may be performed before the start of the separation process, ejecta from the detector 900 may be absent or comprise only the solvent. The wash section 600 may also be configured to draw up solvent from the solvent reservoir 50 so that at the same time, the outside surface of the collection needle 310 may be washed. This may help remove traces of prior collected fractions from the outer surface of the collection needle 310.
[0259] Once solvent has been drawn up into the pump 100, it may be pushed into the buffer section 400. This is depicted in FIG. 6b. The switching valve 200 may be rotated by +45° from its position in FIG. 6a so that the second connecting element 210a now connects ports 1 and 8, the first connecting element 210b now connects ports 0 and 3, and the third connecting element 210c now connects ports 4 and 5. This corresponds to the discharge configuration depicted in FIG. 2b. A fluid flow path is established between the pump 100 and the buffer section 400 in this configuration, with the other port of the buffer section 400 connected to the waste reservoir 700. The solvent drawn up into the pump 100 in the previous step may now be pushed into the buffer section 400. The ejecta from the detector 900 may be directed into the waste reservoir 700 in this configuration.
[0260] The volume of the pump 100 may be chosen to be large enough that the buffer section 400 is reliably filled with the solvent at the end of the pumping process described above.
[0261] Alternatively, if the volume of the pump 100 is not large enough, the above steps of sucking solvent in and pushing it into the buffer section 400 may be repeated until the buffer section 400 is completely filled with the solvent.
[0262] The filling up of the buffer section 400 may be followed by the pump 100 filling up solvent from the solvent reservoir 50 to be used in a subsequent flushing process. This may help increase the efficiency of the collection process and may be of interest when a plurality of closely spaced fractions may have to be collected. Additionally, the process of cleaning and filling up the buffer section 400 and filling up the pump 100 as described above may be repeated after collecting each fraction. This may also help to avoid contamination of any of the fractions with components from any other fraction.
[0263] As FIGS. 6a and 6b further depict, the collection needle 310 may be kept in the wash section 600 for the entire process of preparing the fluidic system 10 for fractionation. The fluidic system 10 may now be used for collection of a first fraction, as depicted in FIGS. 7a and 7b.
[0264] In other words, the steps depicted in FIGS. 6a and 6b may be summarized as filling up the pump 100 and buffer section 400 with cleaning/wash solvent, and washing the outer surface of the collection needle 310 at the same time. The steps may comprise sucking in solvent into the cavity of the pump 100 and filling up the inner cavity of the pump 100 with the cleaning/wash solvent. At the same time, the buffer section 400 may be filled up with cleaning/wash solvent, too. This may comprise dispensing out liquid into the waste reservoir 700 and filling up the buffer section 400. Note that the above steps may also be repeated several times to fill up the solvent inlet tube (which connects the solvent reservoir 50 to the pump 100) to complete the pump priming task. Meanwhile, the outside surface of the collection needle 310 may also be washed. Once this is done, the pump 100 is ready for a subsequent buffer section wash function. This process of filling up the pump 100 may be carried out each time before washing the buffer section 400 when the buffer section is used to enable fraction collection.
[0265] FIG. 7a shows the fluidic system 10 in a fraction collection mode. The switching valve 200 may stay in the discharge configuration until the first fraction that is to be collected, depicted as straight black arrows, is detected in the detector 900 and triggers a movement of the collection needle 310 from the wash section 600 into one of the plurality of collection reservoirs 500, for e.g., into a first collection reservoir 500a. Further, a switching of the switching valve 200 may also be triggered. The switching valve 200 may be switched to the collection configuration depicted in FIG. 2c, such that a flow is established between the ports 0 and 2, allowing collection of the first fraction into the collection reservoir 500a, as depicted in FIG. 7b. Note that an accurate estimation of the time required for any fraction to flow from the detector 900 to the collection needle 310 may be of particular advantage in the process described above.
[0266] The positioning of ports on the switching valve 200 such that the collection configuration of the switching valve 200 is between its discharge and buffer configurations may allow for rapid switching from the discharge configuration to the collection configuration by simply rotating the rotor of the switching valve by 45°. The pump 100 may not be operated while a fraction is being collected with the switching valve 200 in the collection configuration. This may involve, for example, no actuation of a piston of the pump 100 in case the pump 100 comprises a piston. The collection of the first fraction is continued until a second fraction that may be collected arrives at the detector 900.
[0267] The fluidic system 10 may now be switched to a buffer configuration. As regards an explanation for a function of the buffer configuration, reference may again be made to FIG. 7b. On the right of this Figure, an exemplary sample composition chart is depicted as 1000. 1000 depicts the sample composition between a point 1002 and the collection needle 310 (see FIG. 7b). In this chart, the vertical axis relates to the position between point 1002 (corresponding to the top of the chart) and the collection needle 310 (corresponding to the bottom of the chart). Perpendicular thereto, the sample composition is depicted, wherein at the bottom of the chart (corresponding to collection needle 310), 100% of a first sample constituent is present and at the top of the chart (corresponding to the point 1002), 100% of a second sample constituent is present, and the sample constitution changes gradually from an intermediary point (corresponding to port 2) and the top of the chart. That is, at a certain point of time, such a sample composition may be present in the fluidic system 10 where 100% of the second sample is present at point 1002 and decreasing to about 0% at the intermediary point at port 2. That is, at port 2 (and downstream therefrom), 100% of a first sample constituent 1006 may be present and at a point 1002 (and upstream therefrom), 100% of a second sample constituent 1008 may be present. However, between the point 1002 and the port 2, the sample composition may gradually change between these sample constituents.
[0268] Again with reference to FIG. 7b, when collecting a fraction up to the point of time of FIG. 7b, only the first sample constituent 1006 will be collected in the first collection reservoir 500a. However, if the system was continued to be operated in this configuration, the second sample constituent 1008 would also be collected in the first collection reservoir 500a, which may be undesirable.
[0269] However, if directly switching the system to collect the sample in another collection reservoir (e.g., in the second collection reservoir 500b), one would also collect mixed sample constituents.
[0270] The above steps depicted in FIGS. 7a and 7b may thus be summarized as follows. The collection needle 310 may be moved to a first collection reservoir 500a. The fluidic system 10 may stay idle in a discharge configuration until a first target fraction arrives. When the collection time window starts, the switching valve 200 may be switched to the collection configuration for collection of the first fraction into the first collection reservoir 500a till a second target fraction comes. The first target fraction is dispensed into the first collection reservoir 500a through the collection tube 320 and the collection needle 310. At this time, the pump 100 is ‘off’, i.e., switched to zero flow, with no actuation of a piston, for example.
[0271] E.g., to avoid this, the system 10 may be switched to the buffer configuration depicted in FIG. 8a. Thus, the solvent in the buffer section may be used as a separator separating the pure component 1006 (which, at the time of switching is present at the port 2 and downstream therefrom) from the mixture of components 1006 and 1008. Thus, the pure component 1006 present in this section may still be forced into the first collection reservoir 500a in this configuration, without there being a risk of component 1008 also being collected in this collection reservoir 1008 (as there is now buffer solvent 1010 upstream of the component 1006).
[0272] Again, this is further depicted by illustration 1000′ in FIG. 8a depicting the solvents and sample present between port 4 and the collection device 300 in the configuration depicted in FIG. 8a. Notably, between port 2 and the collection device 300, the sample constituent 1006 is present and upstream thereof between the port 4 and the port 2, buffer solution 1010 is present. When continuing to operate the system in this configuration, the sample constituent 1006 will be further collected into the reservoir 500a, until the buffer solution arrives at the collection device 300—see FIG. 8b, and here the illustration 1000″ corresponding to illustration 1000′. That is, in this configuration, in a section upstream of the collection 300, the buffer solution will be present and further upstream the section containing a mix of 1006 and 1008 is present.
[0273] The system can then be switched to the configuration depicted in FIG. 9 allowing the mixed section to be rinsed out of the system to arrive at a state where pure sample component 1008 is present at port 3 (and upstream therefrom). One can then switch the system to the configuration depicted in FIG. 10 to collect the sample component 1008 in a second collection reservoir 500b. In this regard, it is also possible that prior to assuming the exact configuration depicted in FIG. 10, the collection device 300 is positioned in wash section 600, as this may allow the buffer solution initially present between port 2 and collection device 300 be expelled. That is, such a configuration may be assumed until the pure sample component 1008 is present at the collection device 300 (and upstream therefrom), and the system may then be switched to the configuration depicted in FIG. 10, such that the pure sample component 1008 may be collected in collection reservoir 500b, as depicted in
[0274] In other words, starting with the configuration depicted in FIG. 7b, the system 10 may be switched to the configuration depicted in FIG. 8a to switch the buffer section 400 in line. More particularly, the switching valve 200 may be rotated by +90° such that it attains its buffer configuration depicted in FIG. 2d. This may allow the buffer section 400 to be introduced into the flow path such that the first fraction that may still be flowing out of the inlet line into the fluidic system 10 may be directed into the collection reservoir 500a via the buffer section 400. The buffer section 400 may have been filled with a cleaning/wash solvent in a previous step as described above so that the first fraction is not contaminated in flowing through the buffer section 400. An advantage of the buffer section 400 may be to prevent mixing of the first and second fractions that may be collected. This may be achieved as follows.
[0275] The switching valve 200 may be kept in its buffer configuration until all of the first fraction has been dispensed into the collection reservoir 500a. Once again, this time may have been determined with the aid of a peak duration for the first fraction and the time required for the peak to flow down to the collection needle 310, including the volume of the buffer section 400. Note also that some part of the second fraction may flow into the buffer section 400 until the first fraction has been completely dispensed into the collection reservoir 500a (see illustration 1000″ in FIG. 8b). Thus, at this time, the buffer section 400 may be filled up partially with the first fraction, the second fraction, and the solvent (mobile phase).
[0276] In other words, upon arrival of the second fraction the switching valve 200 switches to a buffer section configuration and continues collecting the first fraction via the buffer section 400. Namely, before the second target fraction flows into the collection tube 320, the switching valve 200 is switched to buffer configuration allowing the fluidic system 10 to keep pushing the remaining first target fraction inside the collection tube 320 and collection needle 310 through the pre-filled clean solvent inside the buffer section 400. The buffer section 400 is thus used to prevent mixing between the first and second target fractions. This configuration is maintained until all of the first target fraction is dispensed into the first collection reservoir 500a. At this time, the buffer section 400 may be almost filled up with the first fraction, the second fraction, and the solvent (mobile phase). The buffer configuration may help increase the recovery rate of the first target fraction. At the same time, the buffer section 400 may be used to prevent mixing between the first and second target fractions, thereby reducing carry over.
[0277] Once collection of the first fraction is complete, the switching valve 200 may be switched again, this time to its discharge configuration depicted in FIG. 2c. This brings the fluidic system 10 to the configuration depicted in FIG. 9.
[0278] The first connecting element 210b may now connect the ports 0 and 3, allowing some of the second fraction to flow into the waste reservoir 700. At the same time, the pump 100 may now be brought into fluidic connection with one port of the buffer section 400 while its other port may be connected to the waste reservoir 700. The buffer section 400 may now be cleaned of the mixture of solvent and first and second fraction that may be left over from the previous collection step by pushing the solvent stored in the pump 100. Clean solvent may flow into the buffer section 400 while the mixture of the first and second fraction and the solvent is pushed out into the waste reservoir 700. This may be achieved by actuation of a piston of the pump 100. Further, as FIG. 9 depicts, the collection needle 310 may be moved into a second collection reservoir, 500b, for example. This may prepare the fluidic system 10 for collection of the second fraction.
[0279] FIG. 10 depicts a configuration of the fluidic system 10 for collection of the second fraction into the second collection reservoir 500b. This configuration may be substantially similar to the one depicted in FIG. 7b for collection of the first fraction aside from the difference in collection reservoirs. The switching valve 200 may be switched back to the collection configuration depicted in FIG. 2c and the second fraction flows via the inlet line, the first connecting element 210b, and collection device 300 into the collection reservoir 500b. If a further third fraction is to be collected, the buffer section 400 may once again be connected into the flow path and used for collection without any mixing of fractions.
[0280] In other words, upon completion of collection of the first fraction through the buffer section 400 as described above, the switching valve 200 may switch to the discharge configuration with part of the second target fraction flowing into the waste reservoir 700. During this time, the pump 100 may be actuated to push the mixture of liquids inside the buffer section 400 into the waste reservoir 700 and refill it with clean solvent from the cavity of the pump 100. At the same time, the collection needle 310 may be moved to the next collection reservoir 500b. Then, the switching valve 200 may be switched back to the collection configuration to dispense the second fraction into the second collection reservoir 500b without any mixing and no carry over.
[0281] This may complete a circle of processes for fraction collection with the intermediate buffer configuration enabled.
[0282] FIGS. 11 and 12 depict alternate configurations of the fluidic system 10 described above, where switching of the collection reservoirs from 500a to 500b for collecting the second fraction may be achieved without an intermediate buffer configuration comprising washing of the buffer section 400. As depicted in FIG. 11, once the first fraction has been collected into the collection reservoir 500a, the switching valve 200 may be moved into a discharge configuration (see FIG. 2b), similar to the one depicted in FIG. 7a, but without the pump 100 being operated to push solvent into the buffer section 400. This may be followed by moving the collection needle 310 from the collection reservoir 500a to collection reservoir 500b.
[0283] Note that this is different from the process described above where partial collection of the first fraction was followed by switching the switching valve 200 to a buffer configuration which introduced the buffer section 400 into the flow path. This involved a rotation of the switching valve 200 by +90°. It may be more efficient instead to skip the buffer configuration and rotate the switching valve 200 only by −45° to bring it to the collection configuration (see FIG. 2c).
[0284] Thus, as depicted in FIG. 12, once the connection needle 310 is housed in the collection reservoir 500b, the switching valve 200 is rotated to the collection configuration, that may bring the inlet line in direct connection with the collection device 300 such that the second fraction may flow into the collection reservoir 500b. Since the buffer section 400 is not used in this embodiment, the pump 100 may not need to be filled with a solvent or the buffer section 400 be washed prior to the collection process.
[0285] In other words, in the no buffer configuration, the pump 100 may be always held still. The fluidic system 10 triggers collection when the target fraction arrives. The switching valve 200 switches at a high speed over two configurations: the collection configuration (see FIG. 11) and the discharge configuration (see FIG. 12). This may comprise a no buffer configuration work flow.
[0286] However, carrying out the collection process using these configurations may involve significant amounts of both the first and second fractions flowing into the waste reservoir 700. This is because the collection of the first fraction may have to be terminated earlier and the switching valve 200 switched from a collection configuration to a discharge configuration depicted in FIG. 11 to avoid the second fraction from flowing into the reservoir 500a. Similarly, in order to reliably ensure that the second fraction flows into the reservoir 500b once the switching valve 200 is moved to the position depicted in FIG. 12, some amount of the second fraction may be allowed to flow out into the waste reservoir before switching the switching valve 200 back to the collection configuration. An advantage of the buffer section 400 as described above may be to allow this switching without significant amounts of either a first or second fraction being discharged into the waste reservoir 700. Exemplary embodiments of the switching valve 200 are depicted in FIGS. 13 to 15. FIG. 13a depicts an exemplary embodiment of the rotor 210 of the switching valve 200. As described above, the rotor 210 may comprise the connecting elements 210a, 210b, and 210c, that may be realized as grooves. Connecting element 210b may be an L-shaped groove comprising a long section, 210b1, and a short section 210b2. The section 210b1 may also be referred to as radial section 210b1 and the section 201b2 may also be referred to as circumferential section 210b2. Connecting elements 210a, 210c may lie on either side of the groove 210b. The long section 210b1 may be substantially parallel to a radius of the switching valve 200, whereas the short section 210b2 may be substantially parallel to an arc of the switching valve 200. Connecting elements 210a, 210c may also be substantially parallel to arcs of the switching valve 200. The L-shape connecting element 210b and the groove marked as angle A may be particularly advantageous for continuous flow and reducing back pressure spike when the switching valve 200 switches from one configuration to the next.
[0287] FIG. 13b depicts an exemplary embodiment of the arrangement of ports 0 to 8 on the stator of the switching valve 200 that may be configured to cooperate with the rotor 210. The stator may comprise the plurality of ports 0 to 8 that may be realized as holes or grooves on the stator. As depicted in FIG. 13b, the ports 1 to 8 may be arranged in a circle on the stator. Two small grey grooves 220a, 220b, connected to the second port 2 and the discharge port 3 respectively are also depicted. They may also be of advantage for continuous flow and reducing back pressure spike when the switching valve 200 switches from one configuration to the next as will now be described.
[0288] FIG. 14 depicts an exemplary sequence of states (or connection status of grooves) of the switching valve 200 when it switches from the collection configuration (FIG. 14a) to the discharge configuration (FIG. 14c). As described above, ports 0 and 2 are fluidically connected to each other in the collection configuration, depicted in FIG. 14a, causing fractions eluted from a separation process upstream to be collected into a collection reservoir 500 connected to the second port 2. Then, in order to collect a second fraction, the fluidic system 10 may be switched to a discharge configuration depicted in FIG. 14c where the first port 0 and the discharge port 3 may be fluidically connected. This may involve rotating the rotor 210 anti-clockwise. As depicted in FIG. 14b, the flow from the first port 0 may always be fluidically connected with the second port 2 or the discharge port 3 during the anti-clockwise rotation of the rotor 210 from the collection configuration (FIG. 14a) to discharge configuration (FIG. 14c). Thus, the first port 0 is always fluidly connected to another port in this transition.
[0289] Thus, the flow from port 0 may not be blocked and may not introduce a spike in back pressure. This may be facilitated in particular by, for example, choosing a length of the groove on the second port 2 (depicted in FIG. 13b) such that the short section 210b2 of the connecting element 210b of the rotor 210 and the groove of the second port 2 may span a length of the rotor 210 between ports 2 and 3 as depicted in FIG. 14b. Thus, when the fluidic connection between ports 0 and 2 is broken off when switching between the collection configuration and the discharge configuration, a fluidic connection between ports 0 and 3 is established.
[0290] FIG. 15 depicts an exemplary sequence of states (or connection status of grooves) of the switching valve 200 when it switches from the discharge configuration (FIG. 15a) to the buffer configuration (FIG. 15c). Similar to the switching depicted in FIG. 14, the flow from the first port 0 may always be fluidically connected with the discharge port 3 or the third port 4 during the anti-clockwise rotation of the rotor 210 from the discharge configuration (FIG. 15a) to the buffer configuration (FIG. 15c). Thus, the flow from port 0 may not be blocked and may not introduce a spike in back pressure. Once again, this may be facilitated in particular by, for example, choosing a length of the groove on the discharge port 3 (depicted in FIG. 13b) such that the short section 210b2 of the connecting element 210b of the rotor 210 and the groove of the discharge port 3 may span a length of the rotor 210 between ports 3 and 4 as depicted in FIG. 15b. Thus, when the fluidic connection between ports 0 and 3 is broken off when switching between the discharge configuration and the buffer configuration, a fluidic connection between ports 0 and 4 is established.
[0291] It will be understood that the valve 200 described with reference to FIGS. 13a to 15c may be used in the system and method described with reference to FIGS. 1 to 12. However, the skilled person will understand that the valve 200 described with reference to FIGS. 13a to 15c may also be used independently from the system and method described with reference to FIGS. 1 to 12.
[0292] Overall, embodiments of the present technology thus allow collection of fractions efficiently, with a high recovery rate and less or almost no carry-over, especially for closely placed fractions/peaks and very small volume fraction collection by employing a buffer configuration (flushing out or dispensing remaining liquid inside the collection tube 320 and the collection needle 310 to improve recovery rate and reduce carry-over).
[0293] Whenever a relative term, such as “about”, “substantially” or “approximately” is used in this specification, such a term should also be construed to also include the exact term. That is, e.g., “substantially straight” should be construed to also include “(exactly) straight”.
[0294] Whenever steps were recited in the above or also in the appended claims, it should be noted that the order in which the steps are recited in this text may be accidental. That is, unless otherwise specified or unless clear to the skilled person, the order in which steps are recited may be accidental. That is, when the present document states, e.g., that a method comprises steps (A) and (B), this does not necessarily mean that step (A) precedes step (B), but it is also possible that step (A) is performed (at least partly) simultaneously with step (B) or that step (B) precedes step (A). Furthermore, when a step (X) is said to precede another step (Z), this does not imply that there is no step between steps (X) and (Z). That is, step (X) preceding step (Z) encompasses the situation that step (X) is performed directly before step (Z), but also the situation that (X) is performed before one or more steps (Y1), . . . , followed by step (Z). Corresponding considerations apply when terms like “after” or “before” are used.
[0295] While in the above, preferred embodiments have been described with reference to the accompanying drawings, the skilled person will understand that these embodiments were provided for illustrative purpose only and should by no means be construed to limit the scope of the present invention, which is defined by the claims.
