Application of dispersive liquid-liquid microextraction combined with sweeping micellar electrokinetic chromatography for trace analysis of six carbamate pesticides in apples

A rapid and sensitive method for the multiresidue analysis of six commonly used carbamate pesticides in apples was developed by using dispersive liquid-liquid microextraction (DLLME) coupled with sweeping micellar electrokinetic chromatography (MEKC). Parameters that affect the extraction and sweeping efficiency, Such as the kind and volume of the extraction and disperser solvent, extraction time. salt addition, sample matrix and concentration of organic modifiers in the separation buffer were investigated and optimized. Under optimized conditions. the enrichment factors were achieved in the range from 491 to 1834. The linearity of the method for methiocarb. diethofencarb, carbaryl and isoprocarb was in the range of 6-500 ng g(-1), and for fenobcarb and tsumacide in the range of 9-500 ng g(-1) with the correlation coefficients (r) ranging from 0.9952 to 0.9990. The limits of detection (LODs) at a signal-to-noise ratio of 3 ranged from 2.0 to 3.0 ng g(-1) The recoveries of the six carbamates for apple samples at spiking levels of 20.0 and 100.0 ng g(-1) were 85.5-108.1% and 85.4-113.3%, respectively. The proposed method has been successfully applied to the analysis of the target carbamate residues in apple samples with satisfactory results.