HLB/PDMS-Coated Stir Bar Sorptive Extraction of Microcystins in Shellfish Followed by High-Performance Liquid Chromatography and Mass Spectrometry Analysis

Microcystins (MCs) pose a major threat to shellfish supplies, and humans that have been in contact with or consume contaminated products. To decrease health risks to the public, an efficient and accurate method for the synchronously determination of seven harmful MCs in shellfish samples was developed by employing a hydrophile lipophile balance/polydimethylsiloxane (HLB/PDMS)-coated stir bar sorptive extraction (SBSE) method coupled with high-performance liquid chromatogram and tandem mass spectrometry (HPLC-MS/MS). The most influential factors of SBSE, sample loading pH, extraction time, and desorption time, were optimized and found to be 5, 60 min, and 10 min, respectively. For the MS ionization, all the doubly charged ions of MCs were used as precursors instead of [M + H]+ for the determination of MCs in the multiple-reaction monitoring (MRM) mode. The method was validated in terms of linearity (R2 = 0.9953~0.9991), sensitivity (LOD ≤ 0.6 μg kg−1 and LOQ ≤ 2.0 μg kg−1), precision (RSD ≤ 12.7%), and recovery (51.7 to 72.3%). With this approach, three randomly chosen batches of Patinopecten yessoensis (P. yessoensis), Haliotis discus (H. discus), and Crassostrea virginica (C. virginica) from the local market were tested. MC-RR and MC-LR were detected to be MCs positive, which were probably induced by the diet of planktonic cyanobacteria. The successfully applied HLB/PDMS-coated SBSE and HPLC-MS/MS method exhibited great advantage in fast analysis of low concentrations of MCs in foods to ensure the safety of shellfish and its products.