Determination of oxine-copper residue in paddy field samples by high performance liquid chromatography

The residue analysis method of oxine-copper in paddy water,paddy soil, rice plants, paddy rice straw, rice husk, and coarse rice was development based on high performance liquid chromatography detection. Paddy water, rice plants, paddy rice straw, rice husk, and coarse rice were extracted with acetonitrile and hydrochloric acid(1 mol/L); paddy soil were extracted with acetonitrile and sodium hydroxide(2 mol/L). Paddy water was ready for injection after filtration, while the rest sample extracts were cleaned up with hexane/acetonitrile, and determined by HPLC equipped with UV detector. PBS-acetonitrile(60:40, V/V) was used as mobile phase at a flow rate of 0.8 mL/min, and ultraviolet absorption wavelength was set at 250 nm for UV detector. With the concentration range of 0.05-5 mg/L, there was a good linear relationship between the concentration of oxine-copper with the corresponding chromatographic peak area, the linear equation was y=231.55x-15.064, and the determination coefficient(R2) which reached the significant level was 0.998 5. With fortified levels of 0.05-1 mg/kg, the average recoveries ranged from 83% to 103%, and with relative standard deviation(RSD, n=5) of 1.5%-6.6%. Pre-treatment process of the method was relatively simple, and the sensitivity and accuracy of the method meet with the technical requirements for the analysis of pesticide residues.