Simultaneous determination of trace pesticides in urban precipitation

Thirty-eight pesticides were monitored in precipitation collected in Kitakyushu city. Trace amounts of pesticides were concentrated by passing the precipitation through a XAD-2 resin-packed column. The concentrated pesticides were extracted with dichloromethane from the XAD-2 resin, followed by the addition of three kinds of internal standards to the separate concentrates. The concentrates were analysed by gas chromatography/mass spectrometry with a selected ion monitor (GC/MS-SIM) using a fused silica capillary column for the quantification of 38 kinds of pesticides. In order to evaluate the accuracy of this method, a recovery test was performed, by spiking standard compounds into organic-free water at concentration level of 0.1 μg −1 0.01 μg −1. The recovery efficiencies of 36 pesticides of 38 tested compounds yielded more than 84% and their relative standard deviations were less than 12%. This method was applied 1o monitor pesticides in the precipitation collected in the spring and summer seasons in Kitakyushu city. Ten species of pesticides were detected in the spring sample and nine species in the summer sample. The concentration of fenobucarb, 14 ng −1 was the highest in the spring sample and propyzamide, 26 ng −1, in the summer sample.