IRMS sample introduction system and method

Patent metadata

Field	Value
Publication number	US-10446380-B2
Application number	US-201816130760-A
Country	US
Kind code	B2
Filing date	Sep 13, 2018
Priority date	Jan 12, 2016
Publication date	Oct 15, 2019
Grant date	Oct 15, 2019

Abstract

A sample introduction system for a spectrometer comprises a desolvation region that receives or generates sample ions from a solvent matrix and removes at least some of the solvent matrix from the sample ions. A separation chamber downstream of the desolvation region has a separation chamber inlet communicating with the desolvation region, for receiving the desolvated sample ions along with non-ionized solvent and solvent ion vapors. The separation chamber has electrodes for generating an electric field within the separation chamber, defining a first flow path for sample ions between the separation chamber inlet and a separation chamber outlet. Unwanted solvent ions and non-ionized solvent vapors are directed away from the separation chamber outlet. The sample introduction system has a reaction chamber with an inlet communicating with the separation chamber outlet, for receiving the sample ions from the separation chamber and for decomposing the received ions into smaller products.

First claim

The invention claimed is:

1. A spectrometer, comprising:
a liquid sample preparation arrangement for providing a liquid sample,
a first ionization source to generate sample ions from the liquid sample, and
a desolvation region, arranged to receive or generate sample ions from a solvent matrix, and to remove at least a proportion of the solvent matrix from the sample ions;
a separation chamber positioned downstream of the desolvation region and having a separation chamber inlet in fluid communication with the desolvation region, for receiving the desolvated sample ions along with solvent vapors comprising non-ionized solvent and solvent ions, the separation chamber having electrodes for generating an electric field within the separation chamber, which defines a first flow path for sample ions between the separation chamber inlet and a separation chamber outlet, but which causes unwanted solvent ions and unwanted non-ionized solvent vapors to be directed away from the separation chamber outlet;
a reaction chamber having an inlet in fluid communication with the separation chamber outlet, for receiving the sample ions from the separation chamber and for decomposing the received ions into smaller products;
a second ionization source to receive the products from the reaction chamber and to produce product ions, and
an Isotope Ratio Mass Spectrometer (IRMS) for analysis of the product ions.

2. The spectrometer of claim 1 , wherein second ionization source is one of: inductively-coupled plasma source, microwave induced plasma source, electron impact source, laser ionization source.

3. The spectrometer of claim 1 , wherein ions and non-ionized solvent enter the separation chamber through the separation chamber inlet in a first direction defining a first axis, and wherein sample ions following the first flow path exit the separation chamber through the separation chamber outlet in a second direction defining a second axis, and wherein the first and second axes are not coincident.

4. The spectrometer of claim 1 , wherein the separation chamber further comprises a gas supply for supplying a flow of gas in a direction transverse or counter to the direction of travel of ions as they enter the separation chamber through the separation chamber inlet, so as to cause sample ions, having a first ion mobility or range of ion mobilities, to be directed along the said first flow path towards the separation chamber outlet, but to cause unwanted ions, having a second ion mobility or range of ion mobilities different to the said first ion mobility or range of mobilities, and unwanted non-ionized solvent, to be directed along one or more further flow paths away from the separation chamber outlet.

5. The spectrometer of claim 1 , wherein the electrodes of the separation chamber comprise a first electrode arrangement arranged to generate a DC and/or an AC electric field, so as to cause sample ions, having a first mass to charge ratio or range of mass to charge ratios, to be directed along the said first flow path towards the separation chamber outlet, but to cause unwanted ions, having a second mass to charge ratio or range of mass to charge ratios, different to the said first mass to charge ratio or range of ratios, and unwanted non-ionized solvent to be directed away from the separation chamber outlet.

6. The spectrometer of claim 5 , wherein the unwanted ions have a higher or lower mass to charge ratio or range of mass to charge ratios than that or those of the sample ions, the DC and/or AC component of the first electrode arrangement guiding the said sample ions toward the separation chamber outlet whilst dispersing the said relatively heavier or lighter unwanted ions.

7. The spectrometer of claim 5 , wherein the first electrode arrangement is arranged to generate an asymmetric AC electric field so as to cause unwanted ions to be dispersed within the separation chamber whilst sample ions are directed toward the separation chamber outlet.

8. The spectrometer of claim 5 , wherein the electrodes of the separation region comprise a first electrode arrangement arranged to generate both a DC and an AC electric field and further comprise a second electrode arrangement arranged to generate a DC electric field that accelerates ions in a direction having a component perpendicular to the said first direction defining the said first axis so as to be directed by the first electrode arrangement along the said first flow path towards the separation chamber outlet, but to cause unwanted solvent ions, having a second mass to charge ratio or range of mass to charge ratios, different to the said first mass to charge ratio or range of ratios, and unwanted non-ionized solvent to be directed away from the separation chamber outlet.

9. The spectrometer of claim 8 , further comprising a power supply arranged to supply AC and/or DC voltages to the electrodes, wherein the power supply is configured to supply a first DC voltage to the second electrode arrangement so as to deflect sample ions away from the first direction defining the first axis, wherein the power supply is configured to supply a second DC voltage to the first electrode arrangement so as to accelerate sample ions in a direction having a component perpendicular with the said first axis, and further wherein the power supply is configured to apply an AC voltage to the first electrode arrangement at a frequency that guides the sample ions into the separation chamber outlet.

10. The spectrometer of claim 1 , wherein the desolvation region further includes a heated channel positioned therein, at or adjacent to the separation chamber inlet.

11. The spectrometer of claim 1 , wherein the desolvation region is formed within a desolvation chamber, the sample introduction system further comprising a heated gas supply connected to the desolvation chamber for supply of a heated gas thereto.

12. The spectrometer of claim 1 , wherein the desolvation region is formed within a desolvation chamber, the sample introduction system further comprising a pumping arrangement connected to the desolvation chamber for adjusting the pressure within the desolvation chamber.

13. The spectrometer of claim 12 , wherein the pumping arrangement is further connected to the separation chamber for adjusting the pressure therein.

14. The spectrometer of claim 13 , further comprising a pumping controller for controlling the pumping arrangement so that the pressure, Psampling, within the desolvation chamber, is at least twice the pressure, Psep, in the separation chamber.

15. The spectrometer of claim 1 , wherein the reaction chamber is at atmospheric pressure in use.

16. The spectrometer of claim 12 , wherein the pumping arrangement is further connected to the reaction chamber, the system further comprising a pumping controller for controlling the pumping arrangement so as maintain the pressure in the reaction chamber between around 50 kPa (0.5 Atm) and 200 kPa (2 Atm).

17. The spectrometer of claim 1 , further comprising a counter gas supply for supplying counter gas to the separation chamber outlet, the counter gas being caused to flow in a direction generally opposed to the direction of incidence of the sample ions thereat.

18. The spectrometer of claim 1 , further comprising a CO2 separation unit downstream of the reaction chamber.

19. The spectrometer of claim 1 , wherein the reaction chamber comprises a combustion chamber or an oxidation or pyrolysis chamber.

Assignees

• Thermo Fisher Scient Bremen Gmbh

Inventors

• Makarov Alexander A
• Horning Stevan R

Classifications

• G01N30/7273 Primary

  Desolvation chambers · CPC title

• G01N27/62

  by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode · CPC title

• H01J49/044 Primary

  with means for preventing droplets from entering the analyzer; Desolvation of droplets · CPC title

• G01N15/0266

  with electrical classification · CPC title

• H01J49/0431

  for liquid samples (interfaces to liquid chromatographs G01N30/7233) · CPC title