Abstract: HPLC with fluorescence detector method for the determination of malachite green(MG) and leucomalachite green in aquatic water was established. By orthogonal test the optimal extraction technology was establish. Reduction effect of KBH4 and limit of detection(LOD) of the method were studied. The optimal extraction conditions are extraction time 5 min,volume ratio of sample to dichloromethane 1:1 and extraction times two. MG can be completely reduced by 0.002 g KBH4. Good linear relationship ranges from 0.5 ng/ml to 800 ng/ml with correlation coefficient 0.99977. And the LOD is 0.2 μg/L. The recovery rates range from 86.8% to 93.3% with the relative standard deviations(RSD) of 3.15% to 8.12%. The method is suitable for the trace analysis of MG in aquatic water owing to its high efficiency and convenience.

Key words: malachite green, aquatic water, KBH4, HPLC with fluorescence detector