Determination of cyromazine residues in agricultural commodities using HPLC-UVD/MS

Abstract A high-performance liquid chromatographic (HPLC) method was developed to determineresidues of cyromazine, a triazine insecticide, in agricultural commodities. Cyromazine was extracted with90% aqueous methanol from representative crops which comprised brown rice, oyster mushroom, orientalmelon, watermelon, and Chinese cabbage. Following to evaporation of methanol in the extract, the aqueousconcentrate was acidified to form the protonated cyromazine. Dichloromethane partition was then applied toremove nonpolar co-extractives in the aqueous phase. Strong cation-exchange chromatography using Dowex50W-X4 resin was employed for final purification of the extract. Cyromazine was successfully separated on aZorbax SB-Aq C 18 column showing high retention for polar compounds. Cyromazine was sensitivelyquantitated by ultraviolet absorption at 214 nm. Limit of quantitation (LOQ) of the method was 0.04 mg/kgirrespective of sample types. Each crops were fortified at 3 different concentrations of cyromazine forrecovery test. Mean recoveries from samples fortified at LOQ~2.0 mg/kg in triplicate ranged 80.2~103.3% infive agricultural commodities. Relative standard deviations in recoveries were all less than 6%. A selected-ionmonitoring LC/MS method with electrospray ionization in positive-ion mode was also provided to confirmthe suspected residue. The proposed method was reproducible and sensitive enough to routinely determineand inspect the residue of cyromazine in agricultural commodities.Key words Cyromazine, Residue, HPLC-UVD/MS