Simultaneous determination of eight microcystins in fish by PRiME pass-through cleanup and online solid phase extraction coupled to ultra high performance liquid chromatography-tandem mass spectrometry.

A rapid and sensitive method was developed based on online solid phase extraction coupled to ultra high performance liquid chromatography-tandem mass spectrometry (online SPE-UHPLC-MS/MS) for the simultaneous determination of eight common microcystins (MCs) in fish. Analytes, including MC-LR, MC-RR, MC-LY, MC-LW, MC-YR, MC-WR, MC-LF and MC-LA, were extracted by the solvent of MeOH: water (80:20, v/v) with 0.1% FA, and the extracted solution was cleaned up by one-step PRiME (process, robustness, improvements, matrix effects, ease of use) procedure before online SPE-UHPLC-MS/MS analysis. After the optimization of sample pretreatment conditions and instrumental parameters, method validation experiments were carried out to evaluate the performance of the method Good linearities were obtained in the range of 0.5-20 μg/L with r larger than 0.99. The average recoveries of eight MCs spiked at 2, 10 and 20 μg/kg in fish samples were from 70.5% to 98.9% with relative standard deviations (RSDs) 1.3%-3.5% for repeatability and 2.2%-7.3% for reproducibility. Limits of detections (LODs) were ranged from 0.1 to 0.5 μg/kg and Limits of quantifications (LOQs) were in the range of 0.3-1.5 μg/kg. The developed method was further applied to the analysis of fish samples collected from Lake Taihu, China. MC-LR, MC-YR and MC-RR were detected in the range of 0.5-3.1 μg/kg. The experimental results proved the feasibility of the developed method for the identification and quantification of various MCs in fish products.