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DE-112015001169-B4 - Confirmation of the identity of ions using multiple collision cross-section ("CCS") measurements

DE112015001169B4DE 112015001169 B4DE112015001169 B4DE 112015001169B4DE-112015001169-B4

Abstract

Methods for identifying ions or confirming the identity of ions, comprising: Determining the ion mobility drift time of first ions in the presence of a first buffer gas, Determining the ion mobility drift time of the first ions in the presence of a second, different buffer gas, Determining an ion mobility drift time difference between the ion mobility drift time of the first ions in the presence of the first buffer gas and the ion mobility drift time of the first ions in the presence of the second, different buffer gas, and Identifying or confirming the identity of the first ions based on the ion mobility drift time difference between the ion mobility drift time of the first ions as determined in the presence of the first buffer gas and the ion mobility drift time of the first ions as determined in the presence of the second, different buffer gas.

Inventors

  • Kevin Giles
  • Martin Raymond Green
  • Keith Richardson
  • Jason Lee Wildgoose

Assignees

  • MICROMASS UK LIMITED

Dates

Publication Date
20260513
Application Date
20150310
Priority Date
20140310

Claims (20)

  1. Methods for identifying ions or confirming the identity of ions, comprising: Determining an ion mobility drift time of first ions in the presence of a first buffer gas, Determining an ion mobility drift time of the first ions in the presence of a second, different buffer gas, Determining an ion mobility drift time difference between the ion mobility drift time of the first ions in the presence of the first buffer gas and the ion mobility drift time of the first ions in the presence of the second, different buffer gas, and Identifying or confirming the identity of the first ions based on the ion mobility drift time difference between the ion mobility drift time of the first ions as determined in the presence of the first buffer gas and the ion mobility drift time of the first ions as determined in the presence of the second, different buffer gas.
  2. Procedure according to Claim 1 , wherein the first buffer gas comprises a first gas having a first composition and wherein the second buffer gas comprises a second gas having a second composition, the second composition being different from the first composition.
  3. Procedure according to Claim 2 , wherein the first gas comprises one or more organic gases.
  4. Procedure according to Claim 2 , wherein the first gas comprises one or more inorganic gases.
  5. Procedure according to one of the Claims 2 until 4 , wherein the first gas comprises air, nitrogen, helium, carbon dioxide, oxygen, hydrogen, methane, argon, sulfur hexafluoride, acetylene, ammonia, benzene, butane, neon, nitrogen dioxide or sulfur dioxide.
  6. Procedure according to one of the Claims 2 until 5 , wherein the first gas comprises one or more additives.
  7. Procedure according to Claim 6 , wherein the one or more additives comprise: <1 volume %, 1-2 volume %, 2-3 volume %, 3-4 volume %, 4-5 volume %, 5-6 volume %, 6-7 volume %, 7-8 volume % or 9-10 volume %.
  8. Procedure according to Claim 6 or 7 , wherein the one or more additives comprise a volatile organic compound.
  9. Procedure according to one of the Claims 2 until 8 , wherein the second gas comprises one or more organic gases.
  10. Procedure according to one of the Claims 2 until 8 , wherein the second gas comprises one or more inorganic gases.
  11. Procedure according to one of the Claims 2 until 10 , wherein the second gas comprises air, nitrogen, helium, carbon dioxide, oxygen, hydrogen, methane, argon, sulfur hexafluoride, acetylene, ammonia, benzene, butane, neon, nitrogen dioxide or sulfur dioxide.
  12. Procedure according to one of the Claims 2 until 11 , wherein the second gas comprises one or more additives.
  13. Procedure according to Claim 12 , wherein the one or more additives comprise: <1 volume %, 1-2 volume %, 2-3 volume %, 3-4 volume %, 4-5 volume %, 5-6 volume %, 6-7 volume %, 7-8 volume % or 9-10 volume %.
  14. Procedure according to Claim 12 or 13 , wherein the one or more additives comprise a volatile organic compound.
  15. Method according to one of the preceding claims, wherein the method further comprises a temporal separation of the first ions according to their ion mobility in one or more ion mobility separation devices or spectrometers.
  16. Procedure according to Claim 15 , wherein one or more ion mobility separation devices or spectrometers are arranged in series and/or parallel.
  17. A method according to any of the preceding claims, wherein identifying or confirming the identity of the first ions on the basis of the ion mobility drift time difference between the ion mobility drift time of the first ions as determined in the presence of the first buffer gas and the ion mobility drift time of the first ions as determined in the presence of the second, different buffer gas, comprises a comparison of the ion mobility drift time difference with an expected absolute difference.
  18. Method for mass spectrometry comprising a method according to any one of the preceding claims.
  19. A control system for a mass spectrometer, wherein the control system is designed and configured to: (i) determine the ion mobility drift time of first ions in the presence of a first buffer gas, (ii) determine the ion mobility drift time of the first ions in the presence of a second, different buffer gas, (iii) determine the ion mobility drift time difference between the ion mobility drift time of the first ions in the presence of the first buffer gas and the ion mobility drift time of the first ions in the presence of the second, different buffer gas, and (iv) identify or confirm the identity of the first ions based on the ion mobility drift time difference between the ion mobility drift time of the first ions as determined in the presence of the first buffer gas and the ion mobility drift time of the first ions as determined in the presence of the second, different buffer gas.
  20. Tax system according to Claim 19 , wherein the control system is set up and designed to identify or confirm the identity of the first ions based on the ion mobility drift time difference between the ion mobility drift time of the first ions as determined in the presence of the first buffer gas and the ion mobility drift time of the first ions as determined in the presence of the second, different buffer gas, by comparing the ion mobility drift time difference with an expected absolute difference.

Description

Confirmation of the identity of ions using multiple collision cross-section (“CCS”) measurements Field of invention The present invention relates generally to mass spectrometry and in particular to methods for identifying ions or confirming the identity of ions, to methods for mass spectrometry, control systems for mass spectrometers and mass spectrometers. background The collision cross section (CCS) of an ion measured using an ion mobility separator or ion mobility separator (IMS) can be used to identify a target analyte when compared to a previously measured library value. A collision cross section can be used in conjunction with other measurements, such as ion mass and chromatographic residence time, to add further specificity to the identification of a compound or composition. The US 2010/0127166 A1 reveals shift reagents that selectively interact with functional groups of various substances and cause a structure-selective drift time shift in ion mobility spectrometry, thereby enabling the detection and confirmation of samples by means of ion mobility-based spectrometry. The DE 103 35 156 A1 Disclosing a device for detecting substances of interest in an air sample, comprising a detector, for example an ion capture mobility spectrometer. The detector is operated alternately with high and low drift voltage, and the spectra recorded at both field strengths are compared with reference spectra to determine the presence of the substances. From the WO 2004 / 012 231 A2 A system for controlling the behavior of ion species in a time-varying filter field of an ion mobility-based spectrometer is developed to improve the identification of ion species based on the control of electrical and environmental aspects of sample analysis. The US 2009/0039248 A1 describes an ion mobility spectrometer with an electrode pair arranged approximately in the middle of a drift chamber, between which a high field is applied to change the drift velocity of selected ions and thereby influence their flight time, so that ambiguous peaks can be identified. It is desirable to provide an improved method for identifying ions and confirming the identity of ions. Summary According to one aspect of the invention, a method for identifying ions or for confirming the identity of ions is provided, having the features of claim 1. Embodiments of the proposed method are specified in the related dependent claims. It is not known to identify analytes based on determining their ion mobility under two different conditions or states, for example, by changing the composition of a buffer gas, such as by adding an additive. Similarly, it is not known to identify analytes based on determining their ion mobility under two different conditions, where one or more operating parameters of an ion mobility spectrometer (e.g., a transient DC wave amplitude or effective velocity) may have been changed. One embodiment allows for more precise specificity in confirming the presence of target compounds by reducing false positive identifications. One embodiment makes it possible to identify classes of compounds by, for example, observing a characteristic drift time shift of the ions when the ion mobility conditions are changed. It is known to use a measurement of a collision cross-section for target confirmation. However, the accuracy of such measurements (±2%) can still lead to a degree of ambiguity. Advantageously, the procedure according to one embodiment significantly improves the accuracy of target confirmation. The method according to one embodiment increases the accuracy of analyte identification. For example, according to one embodiment, the drift time difference of analytes induced to migrate in the presence of The procedure for temporarily separating buffer gases (which have different compositions) is particularly advantageous in that it is significantly more robust to changes in the state of the ion mobility separator than the use of an absolute drift time measurement. As a result, the disclosed procedure leads to a significant improvement in precision and accuracy. It should be clear that the various disclosed embodiments are not limited to performing just two measurements, that is, determining the physicochemical or other properties of first ions (or of second ions derived from the first ions) under just two different conditions. Embodiments are considered in which the physicochemical or other properties of the first ions (or of the second ions derived from the first ions) can be determined under third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, and further different conditions. According to a further aspect of the invention, a method for mass spectrometry with the features of claim 18 is provided. A collision cross-sectional area value can be recorded for each buffer gas composition, and a difference in the collision cross-sectional area value between buffer gases can also be recorded. More than one measurement of ion mobility can be performed for