Development and validation of an ultrasound-assisted surfactant-enhanced emulsification microextraction method for liquid chromatographic determination of carbamate residues in fruit juices

Abstract

A microextraction procedure based on ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) was optimized and validated for preconcentration of carbamate pesticides prior to fast determination using high-performance liquid chromatography (HPLC) with monolithic column. The nonionic surfactant (Tween 20) was used as an emulsifier, and chloroform was selected as an extraction solvent. The experimental parameters affecting the extraction efficiency, such as the kind, concentration, and volume of surfactant, the kind of extraction solvent and its volume, salt addition, ultrasonic extraction time, and centrifugation time, were optimized. Under the selected UASEME and HPLC conditions, separation of five carbamate pesticides (carbofuran, carbaryl, isoprocarb, methiocarb, and promecarb) was achieved within 10 min. The linearity of the method was obtained in the wide range of 2–5000 μg L−1, with correlation coefficients of 0.9931–0.9970. The limits of detection were in the range of 0.4–7.0 μg L−1. The relative standard deviations (n = 5) were less than 0.59% and 4.86% for retention time and peak area, respectively. The enrichment factors of the developed UASEME method were in the range of 33–166. The fruit juice samples (at fortified levels of 0.25, 0.50, and 1.00 mg L−1) were successfully analyzed, and the relative recoveries were obtained in the range of 81–115%.