Abstract:

Purpose: Malachite green (MG), leuco malachite green (LMG), crystal violet (CV) and leuco crystal violet (LCV)
residues in fish were determined simultaneously using ultra performance liquid chromatography-tandem mass spectrometry
(UPLC-MS-MS). Methods: Fish samples after addition of internal standards D5-MG, D6-LMG, D5-CV, and D6-LCV were
extracted with acetonitrile and centrifuged, and then the supernatants were applied on a neutral alumina column, blown
almost dry under a stream of nitrogen and re-dissolved in 50% aqueous acetonitrile (by volume) before being subjected to
UPLC-MS-MS analysis. Results: A linear relationship was observed over a concentration range of 1–50 ng/mL for MG and
LMG, and over a concentration range of 1–100 ng/mL for CV and LCV. The limits of detection (LOD) for MG, LMG, CV
and LCV were 0.05 μg/kg and the limits of quantification (LOQ) for all of them were 0.15 μg/kg. Average recoveries from
blank samples spiked at levels of 50, 100 and 200 ng/mL ranged from 87.80% to 110.82%, with relative standard deviation
smaller than or equal to 4.32% (n = 6). Conclusions: This method proved sensitive, accurate and reliable.

Key words: ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS), fish, malachite green(MG), crystal violet (CV), residues