| Abstrakt: |
A multiresidue method was developed for the determination of nitrogen- and phosphorous-containing pesticides (amines, anilides, phosphorothioates, and triazines) by solid-phase microextraction (SPME) in-line coupled to gas chromatography—mass spectrometry (GC/MS). The 85-μm polyacrylate fiber was first dipped into the aqueous sample for a given time and then directly introduced into the heated injector of the gas chromatography—mass spectrometer, where the analytes are thermally desorbed. The method was evaluated with respect to the limit of detection, linearity, and precision. The limit of detection [selected ion monitoring (SIM) mode] depends on the compound and varies from 5 to 90 ng/L. The method is linear over at least 3 orders of magnitude with coefficients of correlation usually ≥ 0.996. In general, the coefficient of variation (precision) is < 10%. The partitioning of the analyte between the aqueous phase and the polymeric phase depends on the hydrophobicity of the compound as expressed by the octanol—water partitioning coefficient Pow. The addition of sodium chloride has a strong effect on the extraction efficiency. This effect increases with decreasing hydrophobicity (increasing polarity) of the compound. |
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