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An analytical method was established for simultaneous determination of chlorantraniliprole, cyantraniliprole and its metabolite J9Z38 in litchi by high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) combined with a modified QuEChERS procedure. The target compounds were extracted from the samples with acetonitrile and then cleaned up with primary secondary amine (PSA) and octadecylsilane (C18). The analytes were separated on a C18 column using V (formic acid aqueous solution) : V (acetonitrile)=15 : 85 as mobile phase and analyzed in multiple reaction monitoring (MRM) mode with positive electrospray ionization (ESI+ ). Quantitative analysis was performed by external standard method using matrix-matched calibration curves. The results showed that the linearity of the target compounds was good (r >0.99) in the range of 0.005-1 mg/L. The limits of quantification (LOQs) were 0.000 5-0.01 mg/kg. The average recoveries of the three pesticides in litchi (whole fruit and pulp) ranged from 76% to 98% at the spiked levels of 0.000 5-0.5 mg/kg, with the relative standard deviations of 2.5% to 9.6%. The method was applied for the detection of twenty commercial litchi samples in Guangzhou City. The results showed that the residues of chlorantraniliprole were 0.001-0.01 mg/kg, and neither cyantraniliprole nor its metabolite J9Z38 were found. The proposed method is convenient, effective and rapid, and is suitable for the simultaneous determination of chlorantraniliprole, cyantraniliprole and its metabolite in litchi. [ABSTRACT FROM AUTHOR]

A sensitive method for the determination of pyraclostrobin and its metabolite BF-500-3 in longan (Dimocarpus longan Lour.) was developed based on high performance liquid chromatographytandem mass spectrometry (HPLC-MS/MS) technique. According to “Guideline for the testing of pesticide residues in crops”, field tests conducted in Guangzhou City of Guangdong Province and Yuxi City of Yunan Province. The residual behavior of pyraclostrobin parent and its metabolite based on longan field trials was investigated. The results showed good average recoveries of 84%-96%, with relative standard deviations of 3.8%-6.7%, at the spiked levels of 0.001, 0.1 and 2 mg/kg in longan. The limit of detection (LOD) was 0.25 × 10−3 mg/kg and the limit of quantification (LOQ) was 0.001 mg/kg. When pyraclostrobin was applied 3-4 times at the dosage of 375 mg/kg with the interval period of 7-10 days, and pre-harvest interval of 5, 7 and 10 days, the residues of pyraclostrobin parent and BF-500-3 in longan were 0.11-0.72 mg/kg and 0.011-0.071 mg/kg, respectively. This study would be helpful to guide the scientific and efficient utilization of this fungicide. Because of the absence of maximum residue limit (MRL) of pyraclostrobin in longan, these results could provide references to facilitate the setting of MRL of pyraclostrobin. [ABSTRACT FROM AUTHOR]

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