Chlorate and perchlorate – LC-MS/MS analytical method validation in a broad range of food commodities

In this study an analytical procedure, based on a modification of the so-called QuPPe-method (quick method for the analysis of numerous highly polar pesticides in food), has been evaluated for routine monitoring of chlorate and perchlorate in a broad range of food matrices. Analytes were extracted with a mixture of water, acidified methanol and dichloromethane, followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) determination. For LC separation HILIC stationary phase provided best results in terms of robustness and column durability. Quantification was performed by isotopic dilution, using the respective 18O isotopically labelled analogues as internal standards. The method was validated in four Nestlé Quality Assurance Centres (NQACs) according to the current EU guidelines for pesticides method validation (SANTE/12682/2019). Trueness of the method ranged from 91.3 to 110.1 %, and intermediate precision was lower than 20 %, except for slight deviations observed in two matrices. Limits of quantification (LOQs) of the method were 0.010 mg/kg for chlorate and perchlorate in all matrices, except for perchlorate in food intended for infants for which the LOQ was 0.002 mg/kg, thus equal or below the maximum residue levels (MRLs) specified on the current EU regulations and recommendations. Therefore, the method fits for monitoring in high routine environments at those decision levels.