Determination of oxathiapiprolin concentration and dissipation in grapes and soil by ultrahigh-performance liquid chromatography-tandem mass spectrometry.

Background: The residue concentrations and dissipation rate of a new oxathiapiprolin fungicide in grapes and soil were investigated to provide an evaluation for the safe use of oxathiapiprolin in grapes. Pesticide residue was extracted by acetonitrile, then purified by solid-phase extraction with an Envi-Carb cartridge and determined by ultrahigh-performance liquid chromatography-tandem mass spectrometry.

Results: The fortified recoveries ranged from 85.2% to 99.0%, with relative standard deviations of 1.7-4.5%. The limit of quantitation for oxathiapiprolin in grapes and soil was 0.002 mg kg . The mean initial deposits of oxathiapiprolin in grapes were 0.345-0.565 mg kg , with half-lives of 8.6-9.2 days. The mean initial deposits of oxathiapiprolin in soil were 0.078-0.273 mg kg , with half-lives of 7.6-12.0 days. The oxathiapiprolin residue in grapes and soil was 0.002-0.022 mg kg and 0.002-0.123 mg kg when sampling 14 days after application, respectively.

Conclusion: The residue in the grapes was less than 0.01 mg kg when sampling 28 days after application, which suggested that the application rate of 20 mg a.i. kg for this fungicide should be used to ensure that treated grapes can be considered safe for humans to consume when sampling 28 days after the final application. © 2016 Society of Chemical Industry.