Determination of field-incurred pyrimethanil residues in persimmon (Diospyros kaki Linn) by liquid chromatography.

Field trials have been carried out to determine the residues of the fungicide pyrimethanil in persimmon (Diospyros kaki Linn) after field treatment. Three treatments using pyrimethanil (PYR 30% WP) were carried out on persimmon trees at a recommended dose rate: the former was sprayed at two different times at 30 and 21 days prior to harvesting; the second was sprayed three times at 40, 30 and 21 days prior to harvesting; and the third was sprayed four times at 40, 30, 21 and 14 days prior to harvesting. The analysis was based on liquid-liquid extraction and solid-phase extraction followed by liquid chromatography with ultraviolet detection at 268 nm. Pyrimethanil was confirmed by high-performance liquid chromatography-mass spectrometry HPLC-MS in the selected ion monitoring mode. The method was validated with spiked fruit samples at concentrations of 0.1 and 0.4 ppm. Average recoveries (three replicates) ranged from 87.1 to 92.1% with relative standard deviations between 4.5 and 11.98%. The calculated limit of detection was 0.02 ppm and the limit of quantitation was 0.07 ppm. After two, three or four applications, pyrimethanil residues on persimmon averaged 0.44, 0.48 or 0.53 ppm, respectively; all of these values were below the maximum residue level established by the Korean Food and Drug Administration (5.0 ppm). This indicates that pyrimethanil residues declined to a level well below the maximum residue level within the 14 day period between the last application and harvesting.