Abstract: An ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the determination of 3 microcystins (MCs) in aquatic products. The samples were extracted with methanol-water (8:2, V/V) and the extract was then cleaned up by multi-walled carbon nanotubes (MWCNTs). The target analytes were detected by UPLC-MS/MS using positive electrospray ionization (ESI+) in the multiple reaction monitoring (MRM) mode. Different MWCNTs were investigated for their suitability as sorbents for dispersive solid phase extraction (DSPE) and the purification conditions were optimized. The efficiency of the optimized DSPE conditions was compared to that of solid phase extraction using HLB column. Both purification methods showed a good linearity (R2 ≥ 0.99) over the concentration range from 1 to 50 μg/L and their limits of quantification were in the range of 0.1–0.2 μg/kg. The average recoveries of three MCs at different spiked levels were 88.7%–95.5% with relative standard deviations (RSDs) equal to or lower than 4.2%. This DSPE method can be suitable for the rapid detection of trace microcystins in aquatic products.

Key words: aquatic product, microcystins (MCs), dispersive solid phase extraction (DSPE), multi-walled carbon nanotubes (MWCNTs), solid phase extraction (SPE)