A method was established for the simultaneous separation and determination of one organophosphorus and three carbamate insecticide residues in food and water samples by solid phase extraction (SPE) followed by analysis using a home-made capillary liquid chromatogram. Various parameters possibly affecting the efficiencies of capillary liquid chromatography (CLC) and SPE were investigated in detail, such as type of SPE column, pH value of samples, type and volume of elution solvent, flow rate of loading sample, salt effect, loading volume, detection wavelength, and type and ratio of mobile phases. Under the optimized experimental conditions, the four insecticides were separated completely within 6 min. The limits of detection and limits of quantification were 0.35-1.20 μg/kg and 1.17-4.00 μg/kg, respectively. Satisfactory recoveries of the SPE-CLC method were achieved for spiked food samples of tomato, cucumber and apple ranging from 72.41% to 107.15% with the relative standard deviations (RSDs) no more than 8.12%, and for spiked tap/lake water samples ranging from 71.45% to 109.25% with the RSDs no more than 9.28%. The method can meet the requirements for multi-residue analysis of insecticides.
Keywords: capillary liquid chromatography (CLC); carbamate; food; insecticide residues; organophosphorus; solid phase extraction (SPE); water samples.