Abstract
The trace-amount analysis has developed by a novel pre-treatment method, liquid phase microextraction (LPME), coupled to gas chromatography-mass spectrometry (GC-MS). The technique involves a fast, solvent-free, pre-concentration and small scale extraction to analyze the target compounds in aqueous samples.The hydroxycarbonyl compounds were determined by using two stepsderivatizations. Dynamic- LPME was applied to the first derivatization,and head-space single drop microextraction was utilized in the secondderivatization. The LOD varied from 0.022- 4.78μg/l. The calibrationcurves were linear at lest 2 orders of magnitude with the R2 ≧0.9941.The precision was within 4 - 11%.The relative recoveries in the rainwater were more than 86%. In real sample (1), it contained 2.54 μg/l ofhydroxyacetone and 0.11μg/l of 3-hydroxy-2-butanone. Thehydroxyacetone was also determined in the sample 2 at the concentrationof 2.39 μg/l.Using 3.5μl organic solvent extracts organophosphorus pesticides in a 20ml aqueous sample. Under optimized conditions, the limits of detection (LOD) with unit Resolution Selected Ion Storage (uSIS) mode depended on the compounds and varied from 0.125 to 0.0055ng/l. The calibration curves were linear at least 3 orders of magnitude with the R2 ≧0.996. In general, the method also gave precision for inter-day and intra-day within 4 to 10%, and the relative recoveries in the lake water were ＞83% . Finally, the results were compared with solid phase microextraction (SPME). It showed that the LPME was an accurate and sensitive technique to detect trace pesticides in aqueous samples.