Gas chromatograph system employing hydrogen carrier gas

Patent metadata

Field	Value
Publication number	US-9632064-B2
Application number	US-201414334282-A
Country	US
Kind code	B2
Filing date	Jul 17, 2014
Priority date	May 13, 2014
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

An injection port for a gas chromatograph (GC) is operated such that, during an injection sequence, an inert gas is used for sample transfer to the analytical column while hydrogen is subsequently utilized for the majority of the analytical separation. This allows for a high degree of chromatographic efficiency, while also reducing unwanted chemical reactions involving hydrogen and/or reactive solvents in a hot injection port. Certain embodiments also provide an increased margin of safety when using hydrogen, since the total flow may be limited such that the concentration of hydrogen in the GC oven never exceeds a safety limit, such as the lower explosive limit.

First claim

What is claimed is:

1. A gas chromatography (GC) system comprising:
a split/splitless sample injector comprising a heater, a gas inlet port a gas outlet port and a split vent port;
a split vent line fluidically coupled to the split vent port and including a proportional valve;
a gas inlet line fluidically coupled to the gas inlet port of the split/splitless sample injector;
a source of inert gas fluidically coupled to the gas inlet line;
a GC analytical column having an inlet that is fluidically coupled to the gas outlet port of the split/splitless sample injector;
a tube fluidically coupled between the gas outlet port of the split/splitless sample injector and the inlet of the GC analytical column;
a source of hydrogen gas;
a hydrogen supply line having a first end fluidically coupled to the source of hydrogen gas and a second end that outlets the hydrogen gas into the tube through a tee-coupler;
a calibrated flow restrictor and a first shutoff valve fluidically coupled between a first and a second portion of the hydrogen supply line; and
an electronic controller electronically coupled to the first shutoff valve,
wherein the electronic controller comprises program instructions to cause the first shutoff valve to supply a flow of hydrogen carrier gas from the source of hydrogen gas to the GC analytical column through the second portion of the hydrogen supply line and the tube during chromatographic separation of sample components within the GC analytical column and during transport of the separated components to a detector.

2. A GC system as recited in claim 1 , wherein the calibrated flow restrictor is configured to limit the flow rate of the hydrogen carrier gas to less than 5 standard cubic centimeters per minute.

3. A GC system as recited in claim 1 , further comprising:
a second shutoff valve and a second calibrated flow restrictor fluidically coupled between the second portion of the hydrogen supply line and the source of inert gas,
wherein the electronic controller is further electronically coupled to the second shutoff valve and comprises further program instructions to cause the second shutoff valve to supply a flow of purge gas from the source of inert gas to the GC analytical column through the second portion of the hydrogen supply line and through the tube during either a system idle time, a time when a sample is being input to the split/splitless sample injector or a time when a sample is being transferred from the split/splitless injector to the GC analytical column.

4. A GC system as recited in claim 1 , wherein the source of hydrogen comprises a hydrogen generator apparatus.

5. A GC system as recited in claim 1 , wherein a portion of the GC analytical column including the inlet end thereof protrudes into an interior of the tube such that an annular gap exists between the GC analytical column and the tube.

6. A method for operating a gas chromatography (GC) system comprising a split/splitless sample injector and a GC analytical column, the method comprising:
(i) introducing a flow of an inert gas into the split/splitless sample injector through a gas inlet port thereof;
(ii) introducing a liquid sample into a sample port of the split/splitless sample injector such that components of the sample are volatilized therein and transferred from an outlet port of the split/splitless sample injector into an inlet end of the GC analytical column under the flow of the inert gas;
(iii) causing hydrogen carrier gas to flow into and through the GC analytical column so as to facilitate separation of the transferred sample components within the GC analytical column and so as to transport the separated components to a detector; and
(iv) ceasing the flow of hydrogen carrier gas into and through the GC analytical column.

7. A method for operating a GC system as recited in claim 6 , further comprising:
repeating the recited steps (i) through (iv),
wherein another liquid sample is introduced into the sample injector during the repeated step (ii).

8. A method for operating a GC system as recited in claim 6 , wherein the step (iii) of causing hydrogen carrier gas to flow into and through the GC analytical column comprises causing the hydrogen carrier gas to flow into and through split/splitless the sample injector and into the inlet end of the GC analytical column from the outlet port of the split/splitless sample injector.

9. A method for operating a GC system as recited in claim 8 , wherein the step (iii) of causing hydrogen carrier gas to flow into and through the GC analytical column is performed by reconfiguration of a gas selection valve that is fluidically coupled between the gas inlet port of the split/splitless sample injector and each of a source of inert gas and a source of hydrogen gas.

10. A method for operating a GC system as recited in claim 6 , wherein the step (iii) of causing hydrogen carrier gas to flow into and through the GC analytical column is performed by introducing a flow of hydrogen gas into a tube that is fluidically coupled between the outlet port of the split/splitless sample injector and the inlet end of the GC analytical column.

11. A method for operating a GC system as recited in claim 10 , further comprising:
(v) causing the inert gas to flow into and through the GC analytical column by introducing a purge flow of the inert as into the tube and into the inlet end of the GC analytical column.

12. A method for operating a GC system as recited in claim 10 , wherein the step (iii) of causing hydrogen carrier gas to flow into and through the GC analytical column comprises introducing the flow of the hydrogen carrier gas into the tube at a flow rate that is greater than a maximum flow rate that can be accommodated by the GC analytical column.

13. A method for operating a GC system as recited in claim 10 , wherein a portion of the GC analytical column including the inlet end protrudes into the tube and wherein the flow of hydrogen is caused to pass into the inlet end of the GC analytical column after passing through an annular gap defined between the GC analytical column and the tube.

Assignees

• Thermo Finnigan Llc

Inventors

• Mccauley Edward B
• Ponciroli Franco
• Magni Paolo

Classifications

• G01N2030/025

  Gas chromatography · CPC title

• G01N30/20 Primary

  using a sampling valve · CPC title

• G01N30/16 Primary

  Injection (G01N30/24 takes precedence) · CPC title

• B01D15/14

  relating to the introduction of the feed to the apparatus · CPC title

• B01D53/025

  with wetted adsorbents; Chromatography (analytical chromatography G01N30/00 - G01N30/96; for liquids B01D15/08) · CPC title