Carrier gas reduction for gas chromatography

Patent metadata

Field	Value
Publication number	US-11255828-B2
Application number	US-202016839016-A
Country	US
Kind code	B2
Filing date	Apr 2, 2020
Priority date	Apr 2, 2020
Publication date	Feb 22, 2022
Grant date	Feb 22, 2022

Abstract

A device for a gas chromatograph (GC) system includes an injector connected to an inlet gas line and a conduit assembly. The inlet gas line is configured to pressurize an input end of a column and to deliver a split or purge flow. The conduit assembly includes a conduit surrounding the input end of the analytical column and coupled to a carrier gas line and a controller. The inlet gas line and the carrier gas line connect to a common gas source. The controller, connected to the conduit, has a first mode delivering a flow of carrier gas which is less than the column flow during an injection period to effect a sample transfer to the column and a second mode delivering a flow of carrier gas greater than the column flow following an injection period to prevent the split or purge flow from entering the column.

First claim

What is claimed is:

1. A device for a gas chromatograph (GC) system comprising:
an injector connected to an inlet gas line, the inlet gas line configured to pressurize an input end of an analytical column and to deliver at least one of a split or purge flow; and
a conduit assembly, including,
a conduit surrounding the input end of the analytical column and coupled to a carrier gas line, the inlet gas line and the carrier gas line configured to connect to a common gas source; and
a controller, connected to the conduit, having a first mode delivering a flow of carrier gas which is less than the column flow during an injection period to effect a sample transfer to the column and a second mode delivering a flow of carrier gas greater than the column flow following an injection period to prevent the split or purge flow from entering the analytical column.

2. A device as in claim 1 , the controller including a valve and calibrated restrictors for delivering two levels of carrier gas flow to the conduit; a T connector interposes an injector and an analytical column, having a midpoint that connects to the conduit.

3. The device of claim 1 , wherein the injector is a split/splitless (SSL) injector.

4. The device of claim 1 , wherein the injector is a programmed temperature vaporization injector (PTV).

5. The device of claim 4 , further comprising a heated precolumn interposing the output of the programmable temperature vaporizing injector and the T connector.

6. The device of claim 1 , wherein the common gas source provides He or H 2 .

7. The device of claim 1 , wherein the inlet gas line provides a flow of not greater than about 10 sccm following the injection period.

8. A gas chromatograph system comprising:
an analytical column;
a detector coupled to an output end of the analytical column; and
the device of claim 1 .

9. The gas chromatograph system of claim 8 , wherein the gas chromatograph detector is a mass spectrometer.

10. A method for supplying a carrier gas to a gas chromatograph, comprising:
providing a carrier gas flow and inlet gas flow to an injector from a common gas source, the inlet gas flow providing a split or purge flow;
changing the carrier gas flow to a first flow rate which is less than the column flow during an injection period to effect a sample transfer to the column during an inject phase;
changing the carrier gas flow to a second flow rate which is greater than the column flow during an resolving phase to prevent the split or purge flow from entering the analytical column;
resolving at least two compounds of the sample with the analytical column; and
detecting the at least two compounds exiting the analytical column.

11. The method of claim 10 , wherein the detector is a mass spectrometer.

12. The method of claim 10 , wherein the common gas source provides He or H 2 .

13. The method of claim 10 , wherein the inlet gas flow during the resolving phase is not greater than about 10 sccm.

14. A method for supplying a carrier gas to a gas chromatograph, comprising:
providing a carrier gas flow and an inlet gas flow to an injector, the carrier gas flow being at a substantially fixed pressure and passing through a flow restrictor, the carrier gas flow and the inlet gas flow provided by a common gas source;
changing an inlet gas pressure during an inject phase to a first pressure sufficient to force at least a portion of the inlet gas flow and at least a portion of a sample onto an analytical column;
changing the inlet gas pressure during a resolving phase to an operating pressure of the analytical column;
resolving at least two compounds of the sample with the analytical column; and
detecting the at least two compounds exiting the analytical column.

15. The method of claim 14 , wherein the inlet gas flow during the resolving phase is not greater than about 10 sccm.

16. The method of claim 14 , wherein the detector is a mass spectrometer.

17. The method of claim 14 , wherein the flow restrictor is sized to provide a volume of carrier gas sufficient to prevent the inlet gas flow from entering the analytical column during the resolving phase.

18. The method of claim 14 , wherein the flow restrictor is sized to provide a volume of carrier gas that exceeds the operating flow of the analytical column by a factor of at least about 1.5.

19. The method of claim 14 , wherein the flow restrictor is sized to provide a volume of carrier gas that exceeds the operating flow of the analytical column by a factor of not more than about 10.

20. The method of claim 14 , wherein the flow restrictor provides a volume of carrier gas between about 1.0 sccm and about 10 sccm.

Assignees

• Thermo Finnigan Llc

Inventors

• Mccauley Edward B

Classifications

• G01N30/10 Primary

  using a splitter · CPC title

• G01N30/32 Primary

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

• G01N30/7206

  interfaced to gas chromatograph (interfaces in general for introducing or extracting samples to be analysed with specially adapted mass spectrometer, see H01J49/04) · CPC title

• G01N30/28

  Control of physical parameters of the fluid carrier · CPC title

• G01N30/16

  Injection (G01N30/24 takes precedence) · CPC title