Abstract: To establish a method for the determination of malathion content in malathion solution by RP- HPLC. The C₁₈ chromatographic column （4.6 mm×150 mm,5 μm） was used to detect the wavelength 225 nm, the mobile phase was methanol water （60∶40）, and the flow rate was 1.0 mL/min. The results showed that malathion in the range of 0.050~1.500 mg/mL, there was a good linear relationship between concentration and peak area, the correlation coefficient was 0.999 8（n=6）, the average recovery rate was 101.6%, RSD was 0.9%; the method is simple, accurate, rapid and reproducible, and can be used for determination of the content of this preparation.

Key words: purified malathion, RP-HPLC, determination of content