Techniques for increasing the throughput of flow injection mass spectrometry

Improvements to the design and operation of a Gilson 215 multiprobe liquid- handling system have resulted in a significant increase in the throughput f or now injection molecular weight characterization of combinatorial chemist ry libraries. The rapid injection sequence, and subsequent increased sample throughput, is effected by directing the entire mobile-phase now through e ach of the injection loops sequentially while isolating or "dead-ending" th e remaining nonactive loops. This mode of operation was accomplished by inc orporating column-switching valves prior to and following the set of eight parallel injectors. Analysis rates are achieved without sacrificing the int egrity of the flow injection peak profile as baseline resolution is maintai ned for all samples, Using this system, the total analysis time for a 96-we ll microtiter plate has been reduced to similar to5 min.