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HPTLC with those from GC/MS for every single one. For confirmation of samples of unknown history, however, the results should be confirmed whenever possible with GC/MS. CONCLUSIONThe study confirmed that the AMD technique can be easily applied to screen for pesticide residues in drinking water samples if a suitable extraction procedure is at hand. This has been demonstrated with the two examples. AMD-HPTLC is a powerful tool for an additional screening in the field of environmental analysis. It is a technique that ideally supplements other chromatographic techniques.

Thirty phenoxyalkanoic acids, other acidic herbicides, and related compounds were derivatized with pentafluorobenzyl bromide to form their pentafluorobenzylic derivatives. Mass spectra are presented. Determination and detection of the derivatives was performed by capillary gas chromatography (GC)/mass spectrometry. With selected- ion monitoring, an optimized GC method, and appropriate time-window setting, the determination of all compounds could be achieved in a single GC run. The determination of ≤1 pg of the target compounds was achieved using electron-impact ionization in selected-ion monitoring mode. Most of the analytes were extracted from tap water, and recoveries were 80–100% when solid-phase extraction was applied with a carefully selected reversedphase-C18 adsorbent. The method enabled the detection of these contaminants from drinking water at the low nanogram-per-liter level when applying a concentration factor of 10 000.

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