Abstract: A simple method based on solid phase extraction (SPE) coupled to high performance liquid chromatography with fluorescence detection was developed for the determination of malachite green (MG) in water samples. MG in water samples was reduced completely to leucomalachite green (LMG) with KBH4. The water samples were purified and enriched with MCX solid-phase extraction cartridges. MG was successfully separated on an Agilent C18 analytical column using a mobile phase consisting of 0.05 mol/L ammonium acetate and acetonitrile (20:80,V/V). Under the optimal conditions, the developed calibration curve was linear in the range of 0.005－0.5 μg/mL for MG with a detection limit of 0.05 μg/L. The mean average recoveries for MG at spike levels of 0.200, 1.00 μg/L and 5.00 μg/L were in the ranges of 91.7%－92.6% in pool water, 87.4%－94.6% in river water, 84.1%－92.6% in sea water, with relative standard deviations (RSD) of 4.5%－5.9%, 2.8%－4.1% and 5.4%－6.5%, respectively. The results show that this method is sensitive, accurate and suitable for the determination of MG residues in water samples.

Key words: malachite green, solid phase extraction, high performance liquid chromatography, water