Abstract |
Industrial wastewater survey samples were analyzed for organic compounds not identified by spectrum matching. Analysis of the samples proceeded from an initial packed column GC/MS analysis for Priority Pollutants, through computerized spectrum matching for other compounds, to the present capillary column GC/MS analysis of a chosen set of sample extracts. Attention was focused on the spectra seen to occur frequently, yet not tentatively identified by spectrum matching. A plan for systematic study of these sample components was devised that included, in step-wise fashion, the use of high resolution gas chromatography, high resolution mass spectrometry, chemical ionization mass spectrometry with positive and negative ion detection, and Fourier transform infrared spectroscopy. Sample cleanup was used at all levels to mitigate interference. For 55 extracts in which components of interest were observed, accurate mass measurement was successfully used to generate chemical formulas in 35 cases. Of these, the results of 16 could be narrowed to one or two possibilities each. Tentative structures were proposed in six cases. Conclusions were: (1) that this type of compound/identification effort is very time and labor intensive, (2) that labor costs are high because highly trained and experienced personnel are required, and (3) that the amount of definitive information that can be obtained by application of any one of the analytical techniques discussed above ranges from minimal to extensive but that integration of information often is a complex problem. |