IDENTIFICATION OF POLLUTANTS IN A MUNICIPAL WELL USING HIGH-RESOLUTION MASS-SPECTROMETRY

elevated incidence of childhood cancer was observed near a contaminate d site. Trace amounts of several isomeric compounds were detected by g as chromatography/mass spectrometry (GC/MS) in a concentrated extract of municipal well water. No matching library mass spectra were found a nd Fourier transform IR and NMR analyses were not feasible due to the low concentration of the compounds. Mass peak profiling from selected- ion-recording data (MPPSIRD) provided the sensitivity and scan speed n ecessary to acquire mass peak profiles at mass resolutions of 10000 to 20000 for the molecular ion (M+.) and 10 fragment ions as capillary G C peaks eluted. Using a profile generation model (PGM), the elemental composition of the molecular ion was determined from the exact masses and abundances of the M, M + 1 and M + 2 profiles. Fragment ion compos itions were determined from their exact masses based on the elements i n the molecular ion. Exact mass differences between the molecular and fragment ions corresponded to unique combinations of atoms for the neu tral losses, Consequent reduction of the number of possible structures for the fragment ions simplified mass spectral interpretation. After inspecting library mass spectra for smaller molecules, isomeric struct ures were hypothesized with cyano and alkylcyano groups attached to te tralin. A literature search found such isomers produced by an industri al polymer synthesis. Three isomers in a standard from polymerization of styrene and acrylonitrile provided the same mass spectra and GC ret ention times as isomers in the extract. (C) 1998 John Wiley & Sons, Lt d.