APPARATUS AND METHOD EMPLOYING ION SHUTTERS FOR ION SEPARATION

• US 20200132626A1
• Filed: 10/01/2019
• Published: 04/30/2020
• Est. Priority Date: 07/30/2015
• Status: Active Grant

• Current Assignee: Smiths Detection-Watford Ltd. (Smiths Group International Holdings Ltd.)
• Original Assignee: Smiths Detection-Watford Ltd. (Smiths Group International Holdings Ltd.)
• Inventors: Piper, Lee J.
• Granted Patent: US 10,942,148 B2
• Time in Patent Office: Days
• CPC Class Codes: G01N 27/622 Ion mobility spectrometry
• CPC Class Codes: G01N 27/623 combined with mass spectrometry
• CPC Class Codes: H01J 49/004 Combinations of spectrometers, tandem spectrometers, e.g. MS/MS, MSn
• CPC Class Codes: H01J 49/025 Detectors specially adapted to particle spectrometers data acquisition H01J49/0036; detectors per se G01T, e.g. G01T1/28, G01T1/29
• CPC Class Codes: H01J 49/061 Ion deflecting means, e.g. ion gates
• CPC Class Codes: H01J 49/062 Ion guides linear ion traps performing mass selection H01J49/4225, mass filters H01J49/421

Abstract

The disclosure relates to methods and apparatus for ion separation, for example using time of flight and ion mobility spectrometry. Ion shutters for use in IMS cells and to methods of operating them are also disclosed. The shutter includes a first shutter electrode and a second shutter electrode. A barrier voltage between these two electrodes is controlled to open and close the shutter to allow ions of interest to pass through the shutter in a drift direction. The control involves varying both: (a) the voltage of the first shutter electrode; and (b) the voltage of the second shutter electrode.

Claims

1-33. -33. (canceled)

34. An ion shutter for an ion mobility spectrometer (IMS) cell, comprising a first shutter electrode and a second shutter electrode, each of the first and second shutter electrodes comprising elongate conductive elements, wherein the first shutter electrode is spaced apart from the second shutter electrode in a drift direction of the IMS cell and the elongate conductive elements of the first shutter electrode are aligned with those of the second shutter electrode in the drift direction.

35. An ion mobility spectrometer (IMS) cell comprising:

an ion shutter comprising a first shutter electrode and a second shutter electrode, each of the first and second shutter electrodes comprising elongate conductive elements, wherein the first shutter electrode is spaced apart from the second shutter electrode in a drift direction of the IMS cell and the elongate conductive elements of the first shutter electrode are aligned with those of the second shutter electrode in the drift direction;

a first shutter voltage provider configured to vary the voltage of the first shutter electrode; and

a second shutter voltage provider configured to vary the voltage of the second shutter electrode,

wherein the first shutter voltage provider and the second shutter voltage provider are configured to control a barrier voltage between the first shutter electrode and the second shutter electrode by varying the voltage of the first shutter electrode and the voltage of the second shutter electrode thereby to control the passage of ions of interest through the ion shutter in a drift direction.

36. The IMS cell of claim 35, wherein the first shutter electrode lies between a reaction region of the IMS cell and the second shutter electrode, and the first shutter voltage provider is configured to match the voltage of the first shutter electrode to a spatially varying profile voltage of the IMS cell prior to opening of the ion shutter.

37. The IMS cell of claim 36, wherein the second shutter voltage provider is configured to open the ion shutter by matching the voltage of the second shutter electrode to the profile voltage.

38. The IMS cell of claim 36, wherein the first shutter voltage provider is configured to close the shutter by controlling the voltage of the first shutter electrode to be different from the profile voltage to provide the barrier voltage.

39. The IMS cell of claim 38, wherein the second shutter voltage provider is configured to match the voltage of the second shutter electrode to the profile voltage after the ion shutter is closed.

40. The IMS cell of claim 39, wherein the first shutter voltage provider and the second shutter voltage provider are configured to reset the ion shutter by changing the voltage of the second shutter electrode to increase the barrier voltage before returning the voltage of the first shutter electrode to the profile voltage.

41. The IMS cell of claim 35, wherein the first shutter voltage provider and the second shutter voltage provider are configured to provide opposing variations in the voltage of the first shutter electrode and the voltage of the second shutter electrode to open and close the ion shutter.

42. The IMS cell of claim 41, wherein the opposing variations are selected to at least partially avoid changes in the mean voltage of the ion shutter.

43. The IMS cell of claim 42, wherein the opposing variations are centered on a profile voltage of the IMS cell.

44. The IMS cell of claim 35, wherein an ion drift region of the IMS cell is arranged to provide the ions of interest to a mass spectrometer.

45. A method of controlling an ion shutter of an ion mobility spectrometer (IMS) cell, the method comprising controlling a barrier voltage between a first shutter electrode and a second shutter electrode to open and close the ion shutter to allow ions of interest to pass through the ion shutter in a drift direction by varying the voltage of the first shutter electrode;

and

varying the voltage of the second shutter electrode,

wherein the first shutter electrode and the second shutter electrode are coplanar.

46. The method of claim 45, wherein controlling the barrier voltage comprises providing opposing variations in the voltage of the first shutter electrode and the second shutter electrode to open and close the ion shutter.

47. The method of claim 45, wherein the opposing variations are selected to at least partially avoid changes in the mean voltage of the ion shutter.

48. The method of claim 45, wherein the voltages of the first shutter electrode and the second shutter electrode are varied with respect to a spatially varying profile voltage of the IMS cell.

49. The method of claim 48, wherein controlling the barrier voltage comprises providing opposing variations in the voltage of the first shutter electrode and the second shutter electrode to open and close the ion shutter, and wherein the opposing variations are centered on the profile voltage.

50. The method of claim 45, further comprising:

providing a voltage of the first shutter electrode which matches the profile voltage and providing a voltage of the second shutter electrode which is different from the profile voltage to close the ion shutter;

providing a voltage to both the shutter electrodes that matches the profile voltage to open the ion shutter; and

providing a voltage of the first shutter electrode that is different from the profile voltage while the voltage of the second shutter electrode matches the profile voltage to close the ion shutter.

51. The method of claim 50, further comprising resetting the ion shutter after it has been closed by varying the voltage of the second shutter electrode to increase the barrier voltage before returning the first shutter electrode to the profile voltage.