A Sensitive UPLC‐MS/MS Method for the Quantification of Clopyralid and Its Conjugate in Plant‐Derived Matrices

ABSTRACT

This study describes the development and validation of an ultra‐performance liquid chromatography‐mass spectrometry (UPLC‐MS/MS) method for the detection, quantification, and confirmation of clopyralid (CLPD) and its conjugate in diverse plant matrices (high water, acid, oil, and protein). The workflow combines the extraction with base hydrolysis and SPE clean‐up, extending applicability beyond conventional single‐residue methods. Conjugated CLPD residues were hydrolyzed to release CLPD in its free form and quantified as CLPD. Samples were extracted with methanol: NaOH, subjected to base hydrolysis, acidified, and purified using pre‐conditioned Oasis HLB SPE cartridges. The final extracts were analyzed by LC‐MS/MS with negative‐ion electrospray ionization. Two MRM transitions were monitored: m / z 189.8 → 145.8 (quantification) and m/z 191.6 → 147.8 (confirmation). Method Validation followed SANTE/2020/12830, Rev.2, evaluating specificity, selectivity, confirmation, matrix effects, linearity, LOD, LOQ, accuracy, precision and extract stability. The method achieved an LOQ of 0.01 mg kg ^{− 1} and LOD of 0.001 mg kg ^{− 1} , with recoveries ranged from 73.7%–103.9% and RSDs below 20%. Its applicability across plant matrices and efficient extraction/clean‐up workflow offer a useful alternative to previously reported single‐residue approaches. The method is sensitive, accurate, and robust for regulatory determination of CLPD and its conjugate quantified as CLPD equivalents in plant commodities.