Determination of Residues of 6 Pyrimidine Fungicides in Surface Water Around Cultivated Land by High Performance Liquid Chromatography-Tandem Mass Spectrometry with Automatic Solid Phase Extraction

A method for the determination of residues of 6 pyrimidine fungicides, including ethirimol, cyprodinil, diflumetorim, ferimzone, pyrimethanil and fenarimol in surface water around cultivated land by high performance liquid chromatography-tandem mass spectrometry with automatic solid phase extraction was proposed. An aliquot (500 mL) of surface water sample after pretreatment was taken, and its acidity was adjusted to pH (7.00±0.05). Then the above water sample was passed through the activated HLB solid phase extraction column (500 mg/12 mL) at a flow rate of 18 mL·min^-1, and eluted with the mixed solution of methanol and acetonitrile at volume ratio of 1\:1. The eluent was collected, and blown to nearly dryness by nitrogen at 45 ℃, and 1 mL of methanol was added for redissolution. The mixed solution was tested by the instrument after mixing well by vortex. It was shown that linear relationships between the mass concentrations and their corresponding MS response values of 6 pyrimidine fungicides were kept in the same range of 0.01-5.00 μg·mL^-1, with detection limits (3S/N) in the range of 0.007-0.033 μg·L^-1. Test for recovery was made according to the standard addition method, giving results in the range of 84.8%-102%, with RSDs (n=5) of the determined values in the range of 1.5%-3.6%, and RSDs (n=6) of the reproducibility in the range of 1.9%-2.9%.