Residue Patterns and Dietary Risk Assessment of Picarbutrazox and Its Metabolite TZ-1E in a Ginseng Planting System

This study established a simple, sensitive, and rapid method for the residual analytical method of picarbutrazox and its metabolites (<i>E</i>)-picarbutrazox (TZ-1E) in ginseng plants, fresh ginseng, and dried ginseng. The samples were extracted and purified using an improved QuEChERS method and determined by HPLC-MS/MS. The linear relationship of the method was good (<i>R</i>² ranging from 0.9935 to 0.9999), the limit of detection was 7.19 × 10^-5 to 1.65 × 10^-3 ng, the limit of quantitation was 0.01 mg/kg, the intra- and interday addition recovery rates ranged from 87.33 to 107.2%, and the relative standard deviation range was 0.58-8.21%. This method was applied to detect residual samples in the field. The results showed that the degradation of picarbutrazox in ginseng plants followed first-order kinetic equations; the <i>R</i>² values were 0.9293 and 0.9430, and the half-lives (<i>t</i>_1/2) were 8.24 and 11.5 d, respectively. It was an easily degradable pesticide (<i>t</i>_1/2 < 30 d). The final residual levels of picarbutrazox in ginseng plants, fresh ginseng, and dried ginseng ranged from 0.0184 to 19.223 mg/kg. A dietary risk assessment was conducted based on the final residual levels of picarbutrazox in fresh and dried ginseng, and the results showed that the chronic exposure risk quotient values of both fresh and dried ginseng were less than 100% (0.1303% for both fresh and dried ginseng). This indicated that the dietary risk of using 10% picarbutrazox suspension concentrate in ginseng was very low and did not pose an unacceptable risk to public health. The results of this study can provide a basis for the development of maximum residue limit for picarbutrazox in ginseng.