Development of Heat-Induced Homogeneous Liquid-Liquid Microextraction for Extraction and Preconcentration of Neonicotinoid Insecticides from Fruit Juice and Vegetable Samples

In this paper, a new version of liquid-liquid microextraction based on heat-induced homogeneous liquid-liquid microextraction has been developed for the extraction and preconcentration of some neonicotinoid insecticides from fruit juice and vegetable samples followed by their determination by high-performance liquid chromatography-diode array detection. In this method, cyclohexyl amine is dissolved in an aqueous solution thermostated at 0 A degrees C. Then, the solution is transferred into a heated water bath. During heating, the solubility of cyclohexyl amine in water is decreased and the produced tiny droplets of the extraction solvent (cyclohexyl amine) are dispersed in whole parts of the solution. The obtained cloudy solution is centrifuged. Finally, an aliquot of the extractant is taken and injected into the separation system for analysis. Various parameters affecting the extraction efficiency such as volume of extraction solvent, temperature, salt addition, and centrifuging rate and time were evaluated. Under the optimum conditions, enrichment factors were obtained in the range of 180-235. The linear ranges of the calibration curves were wide. Limits of detection were in the ranges of 0.38-1.31 and 0.19-0.69 ng mL(-1), in vegetable samples and fruit juices, respectively. Limits of quantification were in the ranges of 1.23-4.09 and 0.64-1.15 ng mL(-1) in the mentioned samples. Finally, the proposed method was applied to analyze the target analytes in different fruit juice and vegetable samples.