COMPARISON OF TANDEM MASS-SPECTROMETRIC TECHNIQUES USING ION-TRAP ANDHYBRID MASS SPECTROMETERS FOR STUDIES OF THE DEGRADATION OF A HERBICIDE BY BIOFILM

The herbicide, methyl 2-4-(2,4-dichlorophenoxy)phenoxy proprionate (di clofop-methyl), and three of its degradation products are identified i n biofilm using tandem mass spectrometry (MS/MS). Sub-samples of a bio film cultured in a flow-through system, with the herbicide diclofop-me thyl in the nutritive solution, were analyzed using two ion-trap mass spectrometers and the data were compared with those obtained using a h ybrid instrument of EBEQ geometry. In order to achieve high throughput , the samples were introduced directly into the ion sources with no fu rther sample preparation, Confirmations were based on data taken for a uthentic standards, The results indicate that data comparable to those obtained using the hybrid instrument could be achieved using ion trap s, despite the complex nature of the biofilm, This is true both of mas s spectra and of product ion MS/MS spectra which were essential for id entification of the individual compounds in these complex mixtures. Fo r high-throughput analyses (20-50 runs daily), the quality of the MS/M S characterization was dependent on the background pressure and the so urce temperature. (C) 1997 by John & Wiley Sons, Ltd.