Claims
- 1. A method of quantitatively detecting small molecules, comprising:
providing an ion source having a target surface carrying a sample material containing a type of small molecules to be detected; operating a laser to apply a plurality of laser pulses to a selected area on the target source, wherein each laser pulse generates a plume of analyte ions from the sample material on the target surface; collisionally damping the analyte ions in the plumes with a damping gas; passing the collisionally damped analyte ions into a triple-quadrupole mass analyzer operated in a multiple-reaction monitoring mode to select ions of a precursor type derived from small molecules of the type to be detected and ions of a product type created by fragmenting ions of the precursor type; counting ions of the product type selected by the triple-quadrupole mass analyzer.
- 2. A method as in claim 1, wherein the step of operating operates the laser at a pulse rate of about 500 Hz or higher.
- 3. A method as in claim 2, where in the pulse rate of the laser is between about 500 Hz and 1500 Hz.
- 4. A method as in claim 3, wherein the pulse rate of the laser is between about 1000 Hz and 1500 Hz.
- 5. A method as in claim 1, further including the step of generating a calibration curve for measurements in the multiple-reaction-monitoring mode.
- 6. A method as in claim 1, wherein the damping gas is provided in a radio-frequency ion guide operated to provide confinement to the analyte ions.
- 7. A method as in claim 1, wherein the step of operating operates the laser at a pulse rate selected to deplete the sample material in the selected area of the target surface within about one second.
- 8. A method of quantitatively analyzing a sample material, comprising:
providing an ion source having a target surface carrying the sample material; operating a laser at a pulse rate of about 500 Hz or higher to apply a plurality of laser pulses to a selected area on the target source, wherein each laser pulse generates a plume of analyte ions from the sample material on the target surface; collisionally damping analyte ions in the plumes with a damping gas; passing the collisionally damped analyte ions into a triple-quadrupole mass analyzer operated in a multiple-reaction monitoring mode to select ions of a precursor type and ions of a product type created by fragmenting ions of the precursor type; counting ions of the product type selected by the triple-quadrupole mass analyzer.
- 9. A method as in claim 8, where in the pulse rate of the laser is between about 500 Hz and 1500 Hz.
- 10. A method as in claim 8, wherein the pulse rate of the laser is between about 1000 Hz and 1500 Hz.
- 11. A method as in claim 8, further including the step of generating a calibration curve for measurements in the multiple-reaction-monitoring mode.
- 12. A method as in claim 8, wherein the damping gas is provided in a radiofrequency ion guide operated to provide confinement to the analyte ions.
- 13. A method as in claim 8, wherein the pulse rate is selected to deplete the sample material in the selected area of the target surface within about one second.
- 14. A system for quantitative analyses of a sample material, comprising:
a target surface carrying the sample material; a laser for generating laser pulses directed to the target surface, the laser being controlled to fire at a pulse rate of about 500 Hz or higher, wherein each laser pulse generates a plume of analyte ions from the sample material on the target surface; a damping gas provided in an ion path of the plumes of analyte ions for collisionally damping the analyte ions in the plumes; a triple-quadrupole mass analyzer disposed in the ion path after the damping gas and operated in a multiple-reaction monitoring mode to select from the analyte ions of a precursor type and ions of a product type created by fragmenting ions of the precursor type; and means for counting ions of the product type selected by the triple-quadrupole mass analyzer.
- 15. A system as in claim 14, wherein the laser is operated at a pulse rate between about 500 Hz and 1500 Hz.
- 16. A system as in claim 15, wherein the pulse rate of the laser is between about 1000 Hz and 1500 Hz.
- 17. A system as in claim 14, further includes a radio-frequency ion guide in which the damping gas is provided, the RF ion guide being operated to provide confinement of the analyte ions.
- 18. A system as in claim 14, wherein the sample material is of a type of small molecules.
RELATED APPLICATION
[0001] This application claims the priority of U.S. Provisional Application No. 60/368,195, filed Mar. 28, 2002.
Provisional Applications (1)
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Number |
Date |
Country |
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60368195 |
Mar 2002 |
US |