Mass spectroscopic reaction-monitoring method

A mass spectroscopic reaction-monitoring method comprising the steps of:

• forcing sequentially generated charge-laden liquid drops to move towards a receiving unit of a mass spectrometer along a traveling path;
• exposing to a laser beam a region that is to be formed of a liquid sample surface, the laser beam being transmitted from an overhead laser directing member and having an irradiation energy sufficient to cause analytes present behind said liquid sample surface relative to said laser unit to be desorbed to fly along at least one flying path;
• introducing a liquid sample to said region so as to form the liquid sample surface at successive points of time that are spaced a plurality of predetermined intervals apart, the liquid sample containing at least one reactant that undergoes an ongoing chemical reaction as a first one of the analytes to form at least one product that co-exist therewith as a second one of the analytes;
• and
• positioning said liquid sample surface relative to said laser beam at each of said successive points of time such that said at least one flying path intersects said traveling path to enable at least one of said coexisting first and second analytes to be occluded in at least one of said charge-laden liquid drops to thereby form at least a corresponding one of first and second ionized analytes.