Mass Spectrometer gain adjustment using ion ratios

• US 20090108191A1
• Filed: 10/30/2007
• Published: 04/30/2009
• Est. Priority Date: 10/30/2007
• Status: Abandoned Application

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Yefchak, George, Staton, Kenneth L., Li, Gangqiang
• Application Number:
  US11/927,995
• Publication Number:
  US 20090108191A1
• Time in Patent Office: Days
• US Class Current: 250/252.100
• CPC Class Codes: H01J 49/0009 Calibration of the apparatus
• 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

Abstract

The gain of the ion detector of a mass spectrometer is calibrated by using the ion detector to measure a ratio of the abundances of at least two ion species having a known abundance ratio. The gain of the ion detector is changed until the measured abundance ratio matches the known abundance ratio.

Claims

1. A method of calibrating the gain of the ion detector of a mass spectrometer, the method comprising:

setting the ion detector to a gain less than that at which the ion detector effectively detects single ions;

using the ion detector, measuring a ratio of abundances of at least two ion species having a known abundance ratio; and

increasing the gain of the ion detector until the measured abundance ratio matches the known abundance ratio.

2. The method of claim 1, in which the ion species having the known abundance ratio are ions of constituent species of air.

3. The method of claim 1, in which the ion species having the known abundance ratio are ions of constituents species of an organic solvent.

4. The method of claim 1, in which the increasing is performed automatically.

5. The method of claim 4, additionally comprising:

determining when the measured ratio matches the known ratio; and

halting the incrementing when the measured abundance ratio matches the known abundance ratio.

6. The method of claim 1, in which:

the detector gain is manually adjustable; and

the incrementing comprises;

communicating the measured abundance ratio to an operator; and

manually incrementing the gain of the ion detector in response to the communicated measured abundance ratio.

7. The method of claim 6, in which:

the incrementing additionally comprises displaying a target abundance ratio that is greater than the known abundance ratio by a predetermined difference; and

the manually incrementing is performed additionally in response to the displayed target abundance ratio.

8. The method of claim 1, in which:

the detector gain is manually adjustable; and

the incrementing comprises;

communicating to an operator a difference between the measured abundance ratio and a target abundance ratio, the target abundance ratio greater than the known abundance ratio by a predetermined difference; and

manually incrementing the gain of the ion detector in response to the communicated difference of the abundance ratios.

9. A mass spectrometer, comprising:

an ion source, a mass analyzer and an ion detector arranged to allow ions to pass from the ion source to the ion detector via the mass analyzer, the ion detector having a controllable gain;

a data acquisition system operable in response to the ion detector to determine a measured ion abundance ratio for at least two ion species having a known abundance ratio; and

a gain adjustment system operable to change the gain of the ion detector to make the measured abundance ratio determined by the data acquisition system match the known abundance ratio.

10. The mass spectrometer of claim 9, in which:

the gain of the ion detector is controllable by a gain control signal; and

the gain adjustment system comprises a comparator operable to generate the control signal by comparing the measured abundance ratio with a target abundance ratio, the target abundance ration greater than the known abundance ratio by a predetermined difference.

11. The mass spectrometer of claim 9, in which the gain adjustment system is additionally operable to generate the gain control signal in a state that sets the ion detector to a gain at which the ion detector detects single-ion events significantly less efficiently than multi-ion events.

12. The mass spectrometer of claim 9, in which:

the gain of the ion detector is controllable manually; and

the gain adjustment system comprises;

a first human interface device coupled to the data acquisition system, the first human interface device operable to communicate the measured abundance ratio to a human operator, and

a second human interface device operable to receive a gain adjustment input from the human operator.

13. A method of calibrating the gain of the ion detector of a mass spectrometer, the method comprising:

using the ion detector, measuring a ratio of abundances of at least two ion species having a known abundance ratio; and

changing the gain of the ion detector until the measured abundance ratio matches the known abundance ratio.

14. The method of claim 13, in which the changing is performed automatically.

15. The method of claim 14, additionally comprising:

determining when the measured abundance ratio matches the known abundance ratio; and

halting the changing when the measured abundance ratio matches the known abundance ratio.

16. The method of claim 13, in which:

the detector gain is manually adjustable; and

the changing comprises;

communicating the measured abundance ratio to an operator; and

manually changing the gain of the ion detector in response to the communicated measured abundance ratio.

17. The method of claim 16, in which:

the changing additionally comprises displaying a target abundance ratio that is greater than the known abundance ratio by a predetermined difference; and

the manually changing is performed additionally in response to the displayed target abundance ratio.

18. The method of claim 13, in which:

the detector gain is manually adjustable; and

the changing comprises;

communicating to an operator a difference between the measured abundance ratio and a target abundance ratio, the target abundance ratio greater than the known abundance ratio by a predetermined difference; and

manually changing the gain of the ion detector in response to the communicated difference of the abundance ratios.

19. A computer-readable medium in which is fixed a program operable to cause a computational device to perform a method that calibrates the gain of the ion detector of a mass spectrometer, the method comprising:

using the ion detector, measuring a ratio of abundances of at least two ion species having a known abundance ratio to provide a measured abundance ratio; and

changing the gain of the ion detector until the measured abundance ratio matches the known abundance ratio.

20. The computer-readable medium of claim 19, in which the method performed by the computational device in response to the program fixed therein additionally comprises:

determining when the measured abundance ratio matches the known abundance ratio; and

halting the changing when the measured abundance ratio matches the known abundance ratio.