Gas inlet system for isotope ratio spectrometer

Patent metadata

Field	Value
Publication number	US-10151690-B2
Application number	US-201415034174-A
Country	US
Kind code	B2
Filing date	Nov 10, 2014
Priority date	Nov 8, 2013
Publication date	Dec 11, 2018
Grant date	Dec 11, 2018

Abstract

A gas inlet system 20 for an isotope ratio spectrometer 1 and a method for coupling analyte gas to an isotope ratio spectrometer 1 are disclosed. A variable volume reservoir 5 is located between a supply of analyte gas 9,11 and a spectrometer 1. The reservoir's internal volume is controllably adjusted at a pre-determined rate to generate a defined flow of analyte gas or mixture to or from the reservoir 5. Analyte gas and carrier gas are taken up by the reservoir 5 on increasing the reservoir's internal volume and then expelled from the reservoir to the spectrometer 1 on decreasing the reservoir's internal volume. An open split 3,8 can be used together with the reservoir 5 to facilitate splitting away and hence dilution of analyte within the reservoir 5. A method for cleaning the gas inlet system 20 is provided, which involves flushing the system with carrier gas.

First claim

The invention claimed is:

1. A gas inlet system for an isotope ratio spectrometer, comprising:
a first supply of analyte gas;
a variable volume reservoir;
a first analyte gas supply line between the first supply of analyte gas and the variable volume reservoir for selectively supplying the analyte gas to the variable volume reservoir;
a reservoir supply line for supplying the contents of the variable volume reservoir to the spectrometer; and
a controller configured to generate a command so as to adjust the volume inside the reservoir at a pre-determined rate, so as to control the flow rate of analyte gas output to the isotope ratio spectrometer as the volume of the variable volume reservoir is adjusted.

2. The gas inlet system of claim 1 , further comprising a valve arranged between the first supply of analyte gas and the variable volume reservoir, the valve having a first position in which analyte gas, from the analyte gas supply is able to flow along the first analyte gas supply line between the first analyte gas supply and the variable volume reservoir, and a second position in which the analyte gas is prevented from flowing between the first analyte gas supply and the variable volume reservoir.

3. The gas inlet system of claim 2 , wherein the valve is further selectively in fluid communication with a second opening.

4. The gas inlet system of claim 3 , wherein the valve has a third position, in which the first analyte gas from the first analyte gas supply is able to flow to the second opening via the valve.

5. The gas inlet system of claim 1 , further comprising a pressure sensor for determining the pressure within the variable volume of the reservoir.

6. The gas inlet system of claim 5 , wherein the pressure sensor comprises a force meter for measuring the force generated between the plunger and the hollow outer cylinder.

7. The gas inlet system of claim 1 wherein the variable volume reservoir comprises one or more deformable walls.

8. The gas inlet system of claim 7 wherein the variable volume reservoir comprises first and second substantially non-deformable end faces and deformable side walls.

9. The gas inlet system of claim 8 , wherein the deformable side walls are corrugated such that the variable volume reservoir is in the form of a concertina or bellows.

10. The gas inlet system of claim 7 , further comprising an outer container inside which is located the variable volume reservoir, and a pumping device for supplying a fluid to or extracting a fluid from a void between the variable volume reservoir and an inner wall or walls of the outer container, the fluid causing the or each deformable wall of the variable volume reservoir to be compressed or expanded so as to vary the volume within the reservoir.

11. The gas inlet system of claim 1 , wherein the minimum volume of the variable volume reservoir is substantially zero.

12. The gas inlet system of claim 1 , wherein the maximum volume of the variable volume reservoir is between 20 and 500 ml.

13. The gas inlet system of claim 1 , wherein the controller is configured to cause the volume within the reservoir to vary at a substantially uniform rate.

14. The gas inlet system of claim 1 , further comprising a multiport inlet between the first supply of analyte gas and the variable volume reservoir, so as to allow selective connection of the first supply of analyte gas and one or more further, alternative supplies of analyte gas.

15. The gas inlet system of claim 1 , wherein the first supply of analyte gas is contained in a sample vial.

16. The gas inlet system of claim 15 , further comprising a supply of carrier gas connected to the sample vial so as to cause carrier gas with entrained analyte gas to exit the sample vial for selective supply to the variable volume reservoir.

17. The gas inlet system of claim 1 , further comprising a referencing unit having first and second input gas lines each arranged to receive a supply of a first and a second reference gas respectively, the first and second reference gases each having a known but different isotopic ratio, the referencing unit being selectively connectable to the spectrometer.

18. The gas inlet system of claim 1 , further comprising a water dryer located in line with the first analyte gas supply line.

19. The gas inlet system of claim 1 , in combination with an isotope ratio spectrometer.

20. The combination of claim 19 , wherein the isotope ratio spectrometer is an isotope ratio Optical Spectrometer (IROS).

21. The combination of claim 19 , wherein the isotope ratio spectrometer is an isotope ratio Mass Spectrometer (IRMS).

22. The gas inlet system of claim 1 , wherein the variable volume reservoir comprises a syringe having a hollow outer cylinder and a plunger configured to move longitudinally of the hollow outer cylinder so as to form therebetween the said variable volume.

Assignees

• Thermo Fisher Scient Bremen Gmbh

Inventors

• Schlueter Hans-Juergen
• Schwieters Johannes
• Wapelhorst Eric
• Krummen Michael

Classifications

• 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

• G01N2030/8411

  Intermediate storage of effluent, including condensation on surface · CPC title

• G01N30/84

  Preparation of the fraction to be distributed · CPC title

• G01N21/11

  Filling or emptying of cuvettes · CPC title

• G01N33/0009 Primary

  General constructional details of gas analysers, e.g. portable test equipment (devices for withdrawing samples in the gaseous state G01N1/22) · CPC title