Ion chromatography tandem mass spectrometry (IC-MS/MS) multimethod for the determination of highly polar pesticides in plant-derived commodities

A new sensitive, fast, and robust analytical method based on a QuPPe (Quick Polar Pesticides) extraction procedure coupled to ion chromatography-tandem mass spectrometry (IC-MS/MS) was developed. The study aimed at the determination of the highly polar pesticides chlorate, perchlorate, ethephon, and 2-hydroxyethylphosphonic acid (HEPA) in different plant food commodities. For achieving an acceptable dynamic range for chlorate and perchlorate and to compensate for matrix effects, the isotopically-labelled internal standards 18O3-chlorate and 18O4-perchlorate and ethephon D4 were applied for calibration. The optimized method was fully validated at levels of 0.010 and 0.100 mg kg−1 for all compounds in the matrices tomato, apple, lemon, sultana, avocado, and wheat according to the actual EU guidance document SANTE/11945/2015. For HEPA and the commodity sultana levels for validation were chosen at 0.050 mg kg−1 and 0.100 mg kg−1. The precision and accuracy of the validation results were determined at hand of five replicates with recovery rates between 93 and 119% and RSDs between 1 and 14%. The use of internal standards for chlorate, perchlorate and ethephon allows the determination in a wide working range between 0.01 and 1 mg kg−1 without interference by matrix effects. The developed analytical methodology is able to meet the strict requirements for the analysis of baby food.