SUB-PARTS-PER-BILLION DETERMINATION OF NITROSUBSTITUTED POLYNUCLEAR AROMATIC-HYDROCARBONS IN AIRBORNE PARTICULATE MATTER AND SOIL BY ELECTRON CAPTURE-TANDEM MASS-SPECTROMETRY

A procedure for the determination of nitro-substituted polynuclear aro matic hydrocarbons (nitro-PAH) on crude air-particulate and soil extra cts is introduced. Elimination of purification and fractionation proce dures was made possible by the use of both a selective ionization meth od, such as electron-capture chemical ionization, and a specific fragm entation process, in an experiment of tandem mass spectrometry (gas ch romatography-electron capture tandem mass spectrometry). Different mas s spectrometric procedures were compared. The best performance was obs erved when the nitro-PAH molecular ions [M](-) were mass-selected by t he first analyzer under multiple reaction monitoring conditions and th en fragmented to NO2- (m/z 46). Detection limits were on the order of hundreds of femtograms, as determined in extracts of real environmenta l samples. This corresponds approximately to 5-15 pg of nitro-PAH per cubic meter of air sampled. Calibration curves were linear over 3 orde rs of magnitude. Applications to contamination from motor vehicle comb ustion and the iron industry are briefly discussed. (C) 1996 American Society for Mass Spectrometry.