Stir bar sorptive extraction coupled to liquid chromatography for the analysis of strobilurin fungicides in fruit samples

A stir bar microextraction (SBSE) procedure for the determination of seven strobilurin fungicides in fruit samples using liquid chromatography (LC) and diode array detection (DAD) has been developed. The samples were sonicated in the presence of ethanol before submitting the extracts to SBSE. The incorporation of drazoxolon as an internal standard before SBSE allowed calibration without the need to use the standard additions method. Under the optimized conditions, detection limits were in the 0.3-2 ng g(-1) range, corresponding to trifloxystrobin and metominostrobin, respectively. The SBSE-LC-DAD procedure showed good repeatability (RSD below 11% in all cases) and provided recoveries of 80-105% from spiked samples. The method was applied to fifteen fruit samples, and low levels of pyraclostrobin and trifloxystrobin were found in two of them. (C) 2010 Elsevier B.V. All rights reserved.