[Study on the determination of N-methylcarbamate insecticides in milk by HPLC]

A high performance liquid chromatographic (HPLC) method using ultraviolet detector (210nm) for simultaneous determination of 5 carbamate insecticides in milk has been developed. Five carbamate insecticides aldicarb, MTMC, carbofuran, carbaryl and MIPC were separated on a reverse phase column (ODS) using methanol-water (45:55) mobile phase, and the resolution was higher than 2.23. The linearity for NMCs standards was good (r = 0.9944-0.9963) and the detection limits of 5 carbamate insecticides were 0.75-3.00 ng. Samples of milk were extracted with acetone. The extraction and partition were combined into one step by saturating the extraction solvent with NaCl and at the same time driving away the water by dichloromethane. The extract was cleaned up by gel permeation (Bio-Beads S-X3). The conditions of Bio-Beads S-X3 column for NMCs multiresidues analysis were studied. The elution solvent was ethyl acetate-cyclohexane (1: 1). The average recoveries of 5 NMCs in samples of milk were above 80%.