Method and system for high-throughput quantitation of small molecules using laser desorption and multiple-reaction-monitoring

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.

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.