Abstract: A gas chromatography-tandem mass spectrometry method was established for the simultaneous determination of the residues of prochloraz and its metabolite 2,4,6-trichlorophenol in kumquats dipped in prochloraz solution. The residual dynamics of prochloraz and 2,4,6-trichlorophenol in kumquats during storage and the risk of dietary exposure to the pesticide through the consumption of kumquats were evaluated in this study. The limits of detection (LODs), average spiked recoveries, and repeatability (expressed as relative standard deviation, RSD) for prochloraz and 2,4,6-trichlorophenol were 1.70 and 0.68 μg/kg, 95.7% and 98.1%, and 5.14% and 3.89%, respectively. The results indicated that the residual levels of prochloraz and 2,4,6-trichlorophenol were increased with increasing concentration of prochloraz and dipping time. The prochloraz concentration in kumquats was increased until a peak on the third day, and then decreased gradually. However, the residual amount of 2,4,6-trichlorophenol in kumquats kept increasing until day 21. The residual concentrations of prochloraz and 2,4,6-trichlorophenol in kumquats dipped in 450 mg/L prochloraz solution for 2 min were 8.180 and 0.069 mg/kg on day 14, respectively. The residual concentration of prochloraz in kumquats dipped in 900 and 2 700 mg/L prochloraz solutions exceeded the maximum residue limit for prochloraz in citrus fruits even after storage for 21 days. The risk of chronic dietary exposure to prochloraz from kumquats after 14 days was within an acceptable range, while the risk of acute dietary risk exposure was larger than 100%, which is not accepted.

Key words: kumquats; prochloraz; 2,4,6-trichlorophenol; residual dynamics; preservation