Optimized Metolachlor, Epoxiconazole and Chlorantraniliprole Mixture Analysis for Aquatic Toxicity Testing Using UHPLC-MS/MS

Abstract

The co-occurrence of pesticides in aquatic ecosystems highlights the need for studies investigating their potential toxicityas mixtures to the aquatic biota. Well-designed studies are essential to assess the presence and toxicity of relevant pesticidemixtures, particularly those such as the chloroacetamide herbicide metolachlor (MET), the triazole fungicide epoxiconazole(EP) and the diamide anthranilic insecticide chlorantraniliprole (CAP), which have not been previously tested, and whose cooccurrenceis possible in waters close to cultivated areas. A solid phase extraction ultra-performance liquid chromatographytandemquadrupole mass spectrometry method was developed to quantify equivalent toxicity concentrations for CAP, EP,and MET in artificial freshwater during acute toxicity tests. Compounds were separated within 1.30 min, showing linearityover the calibration ranges of 2–150 μgL−1 for CAP and 50–3000 μgL−1 for EP and MET. Detection and quantificationlimits were (μgL−1): 0.001 and 0.0037 MET; 0.000038 and 0.00013 EP; and 0.002 and 0.007 CAP, respectively. Precisionand accuracy met intra-assay validation requirements. Recoveries were tested at low and high concentration levels and werebetween 77% and 120%. Additionally, matrix effect showed different behavior among compounds. In an acute toxicity testproposed, MET and EP remained stable (24 h), while CAP decayed 27% ± 4% in the same period. The method proved effectivedespite different concentrations in toxicity testing design.