Abstract: A method was developed for the determination of dithianon residues in apple and soil by using high performance liquid chromatography (HPLC). The residues in samples were extracted with acetonitrile, cleaned up by a modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method, separated on an Agilent Eclipse XDB-C18 column, and then analyzed by HPLC with variable-wavelength detection (VWD) at a wavelength of 250 nm. The analyte was quantified by the matrix-matched external standard method. Under the optimal conditions, the calibration curve showed good linearity in the range of 0.02–5.00 mg/L for dithianon. The average recoveries of dithianon were in the range of 74%–92%, with relative standard deviations (RSDs) of 1.02%–6.20%. The limit of detection (LOD, RSN > 3) of dithianon was 0.005 ng, and the limit of quantitation (LOQ) was 0.02 mg/kg. The half-life of dithianon was 3.8–12.6 and 1.0–8.3 days in apple and soil, respectively. At harvest, apple samples were found to contain dithianon levels below the maximum residue limit (MRL) in China (5 mg/kg). The harvest interval was recommended to be 14 days after the last application.

Key words: dithianon, QuEChERS, high performance liquid chromatography (HPLC), apple, soil, residue