Application of an ultrasound-assisted surfactant-enhanced emulsification microextraction method for the analysis of diethofencarb and pyrimethanil fungicides in water and fruit juice samples

In this work, a simple, practical and environmentally friendly sample pre-treatment method, ultrasound-assisted surfactant-enhanced emulsification microextraction coupled with high performance liquid chromatography-diode array detector/electrospray ionisation mass spectrometry, was developed to determine diethofencarb and pyrimethanil residues in water and fruit juice samples. Tween 80 was used as an emulsifier and carbon tetrachloride was chosen as the extraction solvent, and no dispersive organic solvent was needed, which is typically required in common dispersive liquid-liquid microextraction methods. Several variables, such as the type and volume of extraction solvent and surfactant, extraction temperature and ultrasound extraction time were investigated and optimised. Under optimal conditions, the enrichment factors were 265 and 253 for diethofencarb and pyrimethanil, respectively. The limits of detection (LODs), calculated as three times the signal-to-noise ratio (S/N), were 0.01 mu g L(-1) for both diethofencarb and pyrimethanil. The linearity of the method was obtained in the range of 0.05-2000 mu g L(-1), with correlation coefficients of 0.9994-0.9998. The water (at fortified levels of 0.1 and 1.0 mu g L(-1)) and fruit juice samples (at fortified levels of 0.1 and 1.0 mu g L(-1)) were successfully analysed using the proposed method, and the relative recoveries were in the range of 88-114%, 93-111%, 86-117% and 94-101%, respectively. (C) 2011 Elsevier B.V. All rights reserved.