Analysis of pyraflufen-ethyl residues in apples and soil by high-performance liquid chromatography

Abstract

A new method was developed to analyse pyraflufen-ethyl residues by high-performance liquid chromatography (HPLC). The UV detector was used for routine analysis and the ion-trap MS was used to confirm the identity of the compound. The residue levels of the pesticide and its dissipation rate in apples and soil in an apple orchard of Beijing were also studied. Primary secondary amine (PSA) and octadecyl (C18) solid-phase extraction (SPE) cartridges were applied for the determination of pyraflufen-ethyl residues in apples and soil, respectively. The limit of detection was estimated to be 1.6 ng, and the limit of quantification of pyraflufen-ethyl in the samples was 0.01 mg kg−1. Average recoveries were between 90.1 and 102.1% at three spiking levels of 0.01, 0.1, and 1 mg kg−1, and relative standard deviations were less than 10% throughout the whole recovery test. A PSA column was found to provide effective cleanup for apples extract in the determination of pyraflufen-ethyl, and C18 could remove the greatest number of sample matrix interferences in soil. A dissipation study showed that the half-life obtained for pyraflufen-ethyl in soil was approximately 11.89 days at 1.5 times of the recommended dosage, and no pyraflufen-ethyl residues were detected in apples at harvest.