ISOMER-SELECTIVE IONIZATION OF CHLORINATED AROMATICS WITH LASERS FOR ANALYTICAL TIME-OF-FLIGHT MASS-SPECTROMETRY - FIRST RESULTS FOR POLYCHLORINATED DIBENZO-P-DIOXINS (PCDD), BIPHENYLS (PCB) AND BENZENES (PCBZ)

The combination of laser induced Resonance-Enhanced Multi-Photon Ioniz ation (REMPI) and Time-Of-Flight mass spectrometry (TOF) represents a useful tool for detection of trace quantities of organic substances. R EMPI spectra (i.e. laser UV spectra) as well as laser induced mass spe ctra of several aromatic compounds are presented. The possibility of i somer-selective ionization is demonstrated by REMPI ionization spectra of isomeric compounds: Spectra of three dichlorodibenzo-p-dioxin isom ers, three tetrachlorobenzene isomers and three dichlorobiphenyl isome rs are shown. Finally the potentiality of laser mass spectrometry in t he field of environmental analysis is discussed.