Mass spectrometer interface

1. A method of providing ionized particles of a sample to a mass spectrometer, comprising:

introducing a mixture of gas and said ionized particles from a source of high pressure into an inlet of a channel;

expanding said mixture into said channel;

maintaining a pressure in said channel between about 1 and 100 Torr;

slowing said gas within said channel to provide a substantially laminar flow proximate an exit of said channel; and

sampling said ionized particles proximate said exit, for analysis in said mass spectrometer.

2. The method of claim 1 , wherein said channel provides a tortuous path for said mixture of gas creating a region of disturbance for said gas within said channel.

3. The method of claim 1 , wherein said channel has a generally round cross-section proximate said region of disturbance, and flow of said gas becomes generally laminar within a distance equal to about twice said diameter from said region of disturbance.

4. The method of claim 1 , wherein said tortuous flow is guided around a barrier within said channel.

5. The method of claim 3 , wherein said channel guides said gas around a bend having an angle of at least 20 degrees.

6. The method of claim 4 , further comprising colliding said ionized particles and attached impurities with a wall of said channel, so as to promote liberation of at least some of said ionized particles from said impurities.

7. The method of claim 6 , further comprising deflecting said ionized particles into said mass spectrometer using at least one electrode.

8. The method of claim 7 , wherein said deflecting comprises using at least one electrode upstream of said mass spectrometer to pulse said ionized particles, so as to facilitate separation of at least some of said ionized particles.

9. The method of claim 7 , further comprising maintaining a pressure in said channel which is less than atmospheric pressure.

10. The method of claim 9 , wherein said gas proximate said exit is at a pressure in the range of 1-10 Torr.

11. The method of claim 9 , wherein said gas proximate said exit is in at a pressure in the range of 1-2 Torr.

12. The method of claim 2 , further comprising introducing a reagent into said channel proximate said region of disturbance, so as to promote reactions between said reagent and said ionized particles.

13. The method of claim 2 , further comprising introducing a second mixture of ionized particles and any attached impurities into said channel proximate said region of disturbance, so as to promote ion-ion reactions between said ionized particles of said first and second mixtures.

14. The method of claim 2 , further comprising introducing electrons into said channel proximate said region of disturbance, so as to promote interaction between said electrons and said first mixture of ionized particles and any attached impurities.

15. The method of claim 1 , wherein said sampling occurs in a region proximate said exit having a pressure in the range of 1-10 Torr.

16. The method of claim 1 , wherein sampling occurs in a region proximate said exit having a pressure in the range of 1-2 Torr.

17. An apparatus for providing ionized particles of a target sample to a mass spectrometer, said ionized particles having characteristic mass to charge (m/z) ratios, said apparatus comprising: a channel for guiding a flow of gas from an inlet to an outlet; said channel including a plurality of channel sections having progressively larger cross-sections for slowing said flow of gas, said outlet being provided at a channel section in which flow of said gas has been slowed to be generally laminar to sample ionized particles from said flow generally perpendicular to said flow.

18. The apparatus of claim 17 , wherein said exit is in at least the third channel section downstream of said sample inlet.

19. The apparatus of claim 17 , wherein said channel has first, second and third sections with progressively larger diameters, said first section having a cross-sectional diameter of between 4-10 mm, said second section having a cross-section diameter of between 5-15 mm, said third section having a cross-section diameter of between 10-30 mm.

20. A method of providing ionized particles of a sample to a mass spectrometer, comprising:

introducing a mixture of gas and said ionized particles from a source of high pressure into a channel;

wherein said channel provides a tortuous path for said mixture of gas creating a region of disturbance for said gas within said channel to aid in liberating at least some of said ionized particles from impurities in said mixture;

slowing said gas within said channel, downstream of said region of disturbance to provide a substantially laminar flow proximate an exit of said channel;

sampling said ionized particles proximate said exit, for analysis in said mass spectrometer; and

wherein substantially all of said ionized particles sampled at said exit have passed through said region of disturbance.

21. A method of providing ionized particles of a sample to a mass spectrometer, comprising:

introducing a mixture of gas and said ionized particles from a source of high pressure into a channel;

slowing said gas within said channel to provide a substantially laminar flow proximate a sampling orifice of said channel; and

providing an evacuation port downstream of said sampling orifice to maintain a pressure in said channel which is less than atmospheric pressure.