A simple and sensitive method for simultaneous analysis of multiresidual fungicides in water samples by HPLC-ESI-MS/MS

Abstract

A sensitive multiresidual analytical method for simultaneous analysis of 9 strobilurin fungicides and 13 amide fungicides in water samples was developed and optimized. The method was based on solid-phase extraction (SPE) followed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). In this method, different mobile phase modifiers were investigated to enhance ionization efficiency and affect chromatographic separation. The following parameters that affect the SPE procedure efficiency were optimized: the column type, the wash solvent and the elution solvent. Qualitative and quantitative detection of the analytes were carried out under multiple reaction monitoring (MRM) in positive ionization mode after chromatographic separation on a Symmetry C18 (150 mm × 2.1 mm × 3.5 μm) column. The recoveries of the SPE ranged from 70.18 to 108.87%, all recoveries were acceptable, with relative standard deviation (R.S.D.) ≤16.71%. The limits of quantification (LOQ, S/N = 10) varied between 0.003 and 0.03 μg L⁻¹ (except for fenhexamid, 0.3 μg L⁻¹). The developed and optimized method was successfully applied for the analysis of environmental water samples as well as tap water samples in China, influenced by agriculture. The most frequently detected fungicides were azoxystrobin, metalaxyl and dimethomorph (Z, E) in the investigated samples, the highest concentration level of metalaxyl was 0.217 μg L⁻¹ in the Pu river.