Sample injector with metering device balancing pressure differences in an intermediate valve state

Patent metadata

Field	Value
Publication number	US-9435773-B2
Application number	US-200913375884-A
Country	US
Kind code	B2
Filing date	Jun 3, 2009
Priority date	Jun 3, 2009
Publication date	Sep 6, 2016
Grant date	Sep 6, 2016

Abstract

A sample injector ( 200 ) for use in a fluid separation system ( 10 ) for separating compounds of a fluidic sample in a mobile phase, the sample injector ( 200 ) comprising a switchable valve ( 202 ), a sample loop ( 204 ) in fluid communication with the valve ( 202 ) and configured for receiving the fluidic sample, a metering device ( 206 ) in fluid communication with the sample loop ( 204 ) and configured for introducing a metered amount of the fluidic sample on the sample loop ( 204 ), and a control unit ( 208 ) configured for controlling switching of the valve ( 202 ) to transfer the sample loop ( 204 ) between a low pressure state and a high pressure state via an intermediate state and for controlling the metering device ( 206 ) during the intermediate state to at least partially equilibrate a pressure difference in the sample loop ( 204 ) between the low pressure state and the high pressure state.

First claim

The invention claimed is:

1. A sample injector for use in a fluid separation system for separating compounds of a fluidic sample in a mobile phase, the sample injector comprising:
a switchable valve;
a sample loop in fluid communication with the valve and configured for receiving the fluidic sample;
a metering device positioned so as to form a part of the sample loop and configured for introducing a metered amount of the fluidic sample into a portion of the sample loop; and
a control unit configured for controlling the valve to switch among a first position, a second position and an intermediate position in order to transfer the sample loop between a low pressure corresponding to the first position of the valve and a high pressure corresponding to the second position of the valve,
the control unit being further configured for controlling the metering device to vary the pressure in the sample loop, while the valve is in the intermediate position, between the low pressure for loading the fluidic sample and the high pressure for driving the mobile phase,
wherein the metering device and the sample loop are in fluid communication in each of the first position and the second position of the valve.

2. The sample injector of claim 1 , wherein the control unit is configured for controlling the metering device while the valve is in the intermediate position to perform a decompression in the sample loop before transferring the sample loop to the low pressure.

3. The sample injector of claim 2 , wherein the control unit is further configured for controlling the metering device for performing the decompression by retracting a metering piston.

4. The sample injector of claim 1 , wherein the control unit is configured for controlling the metering device while the valve is in the intermediate position to perform a precompression in the sample loop before transferring the sample loop to the high pressure.

5. The sample injector of claim 4 , wherein the control unit is further configured for controlling the metering device for performing the precompression by pushing forward a metering piston.

6. The sample injector of claim 1 wherein the metering device is further configured as a high pressure metering device.

7. The sample injector of claim 1 , wherein the metering device is further configured for providing a pressure of about 10 MPa to about 100 MPa as the high pressure.

8. The sample injector of claim 1 , wherein the metering device is further configured for providing the same pressure as a mobile phase drive, adapted to drive the mobile phase through a separation column of the fluid separation system.

9. The sample injector of claim 1 , wherein the metering device is further configured for increasing the pressure in the sample loop, before the valve is switched from the first position to the second position, to a system pressure of a mobile phase drive, adapted to drive the mobile phase through a separation column of the fluid separation system.

10. The sample injector of claim 1 , wherein the valve comprises a first valve member and a second valve member, wherein at least one of the first and second valve members is adapted to be moved with respect to the other, one of the first and second valve members comprises a plurality of ports, and the other comprises at least one groove for fluidly coupling respective ones of the ports in dependency on a relative movement position of the first and second valve members with respect to each other.

11. The sample injector of claim 10 , wherein the plurality of ports and the at least one groove are configured such that, when the valve is in the intermediate position and the pressure in the sample loop succeeding the low pressure and preceding the high pressure, a pumping system adapted to drive the mobile phase through a separation column is still in fluid communication with the separation column, and the sample loop is no longer at an atmospheric pressure and not yet in fluid communication with the separation column.

12. The sample injector of claim 10 , wherein the plurality of ports and the at least one groove are configured such that, when the valve is in the intermediate position and the pressure in the sample loop succeeding the high pressure and preceding the low pressure of the sample loop, a pumping system adapted to drive the mobile phase through a separation column is still in fluid communication with the separation column, and the sample loop is no longer at a pressure of the pumping system and not yet at an atmospheric pressure.

13. The sample injector of claim 10 , wherein the plurality of ports and the at least one groove are configured such that, when the pressure in the sample loop is at the high pressure, the sample loop is in fluid communication with a pumping system adapted to drive the mobile phase through a separation column and is in fluid communication with the separation column.

14. The sample injector of claim 10 , wherein the plurality of ports and the at least one groove are configured such that, when the pressure in the sample loop is at the low pressure, the sample loop is not in fluid communication with a pumping system adapted to drive the mobile phase through a separation column and is not in fluid communication with the separation column.

15. The sample injector of claim 10 , wherein the plurality of ports and the at least one groove are configured such that a first position of one of the at least one groove is aligned with one of the plurality of ports when the pressure in the sample loop is at the low pressure, a second position of the one of the at least one groove is aligned with the one of the plurality of ports when the pressure in the sample loop is at the high pressure, and a third position of the one of the at least one groove is aligned with the one of the plurality of ports when the pressure in the sample loop is being transferred between the low pressure and the high pressure, the third position defining a stop position of the one of the plurality of ports.

16. The sample injector of claim 1 , further comprising a pressure sensor arranged for measuring the pressure in the sample loop and for providing the measured pressure to the control unit as a basis for the controlling of at least one of the metering device and the valve.

17. The sample injector of claim 1 , wherein the control unit is further configured for controlling the valve to switch so that a fluidic path in which both the metering device and the sample loop are arranged is selectively brought in or out of fluid communication with a mobile phase drive, adapted to drive the mobile phase through a separation column of the fluid separation system.

18. A fluid separation system for separating compounds of a fluidic sample in a mobile phase, the fluid separation system comprising:
a mobile phase drive adapted to drive the mobile phase through the fluid separation system;
a separation unit adapted for separating compounds of the fluidic sample in the mobile phase; and
the sample injector of claim 1 for introducing the fluidic sample into the mobile phase.

19. A method of operating a sample injector in a fluid separation system for separating compounds of a fluidic sample in a mobile phase, the method comprising:
introducing, by a metering device, a metered amount of the fluidic sample on a sample loop in fluid communication with a switchable valve and with the metering device;
controlling the valve to switch among predetermined valve positions to transfer the sample loop between a low pressure and a high pressure;

Assignees

• Glatz Bernd
• Kretz Wolfgang
• Agilent Technologies Inc

Inventors

• Glatz Bernd
• Kretz Wolfgang

Classifications

• G01N30/32

  of pressure or speed (G01N30/36 takes precedence) · CPC title

• G01N2030/027

  Liquid chromatography · CPC title

• G01N30/20 Primary

  using a sampling valve · CPC title

• G01N30/36

  in high pressure liquid systems · CPC title

• G01N2030/207

  with metering cavity, e.g. sample loop · CPC title