A rapid miniaturized residue analytical method for the determination of zoxamide and its two acid metabolites in ginseng roots using UPLC-MS/MS.

A miniaturized residue method was developed for the analysis of the fungicide zoxamide and its metabolites in dried ginseng root. The zoxamide metabolites, 3,5-dichloro-1,4-benzenedicarboxylic acid (DCBC) and 3,5-dichloro-4-hydroxymethylbenzoic acid (DCHB), are small acid molecules that have not been previously extracted from the ginseng matrix with common multiresidue methods. The presented extraction method effectively and rapidly recovers both the zoxamide parent compound and its acid metabolites from fortified ginseng root. The metabolites are extracted with an alkaline glycine buffer and the aqueous ginseng mixture is partitioned with ethyl acetate. In addition, this method avoids the use of derivatization of the small acid molecules by using UPLC-MS/MS instrumental analysis. In a quantitative validation of the analytical method at three levels for zoxamide (0.007 (LOD), 0.02 (LOQ), and 0.2 mg/kg) and four levels (0.07 (LOD), 0.2 (LOQ), and 0.6 and 6 mg/kg) for both metabolites, acceptable method performances were achieved with recoveries ranging from 86 to 107% (at levels of LOQ and 3×, 10×, and 30× the LOQ) with <20% RSD for the three analytes in accordance with international guidelines.1.