DETERMINATION OF TRACE AMOUNTS OF ACETONE IN ROOM AIR BY ATMOSPHERIC-PRESSURE IONIZATION MS

Determination of trace amounts of acetone at (sub-ppm level) in air by atmospheric pressure ionization mass spectrometry (API-MS) was studie d. Air samples were directly introduced to the ion source of the instr ument without pre-concentration. This technique (positive mode) is als o used for real-lime analysis of air samples with rapid scanning, and has been shown to be highly sensitive for acetone (at sub-ppm levels). The peaks at m/z 19, 37, 55, 73, 91; corresponded to protonated water clusters of (H2OH+, ((HO)-O-2H+, (H2OH+, (H2OH+, and (H2OK+, respecti vely. The peak at m/z 47 was due to (C2H5OHH+, and that at 59 due to ( (CH3)(2)COH+ (acetone). They showed good repeatability with a relative standard deviation of less than about 5%. The API-MS voltage response produced a straight line in the approximate range 0.01 to 0.1 ppm of acetone in air.