An effective analytical method was developed for the detection and quantification of polyoxin D in butterbur using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Samples were extracted using acidified deionised water and purified via solid-phase extraction (SPE) using an HLB cartridge. An external matrix-matched standard calibration curve was prepared, which provided an excellent linearity with a coefficient of determination (R2) ⩾0.999. Limits of detection (LOD) and quantification (LOQ) were 0.015 and 0.0.05μg/g, respectively. The developed method was validated in terms of recovery performance using two fortification levels in triplicate. The storage stabilities of the various field samples were also determined. Our method provided consistent recovery (86.26-87.37%) with a relative standard deviation (RSD) of <5%, and was successfully applied to field-treated butterbur grown under greenhouse conditions and collected at various times following commercial fungicide application. As expected, a gradual degradation of polyoxin D was observed, with a half-life (t1/2) of 2.11d being recorded. Finally, we propose that the developed method can be extrapolated to other crops for routine analysis and can be used to determine the pre-harvest intervals (PHIs), thus preventing the development of antibiotic resistance genes in humans and in the environment.
Keywords: Butterbur; Dissipation; Fungicide; Half-life; Polyoxin D; UPLC-MS/MS.
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