Determination of organochlorine pesticides and chlorobenzenes in strawberries by using accelerated solvent extraction combined with sorptive enrichment and gas chromatography/mass spectrometry

An analytical scheme for the determination of several organochlorine pestic ides like hexachlorocyclohexanes (HCHs) and DDX compounds (p,p ' -DDE, p,p ' -DDD, and p,p ' -DDT) as well as chlorobenzenes in strawberries has been developed. The procedure is based on aqueous accelerated solvent extraction (ASE) followed by solid-phase microextraction (SPME) or stir bar sorptive extraction (SBSE) and subsequent thermodesorption-gas chromatography/mass s pectrometry analysis. A 65 pm polydimethylsiloxane/ divinylbenzene fiber wa s chosen for the SPME experiments. Significant SPME and ASE parameters were optimized using spiked water and strawberry samples. For the ASE of the or ganochlorine compounds, a water-acetone mixture (90 + 10, v/v) as the extra ction solvent, an extraction temperature of 120 degreesC, and 2 cycles of 1 0 min extraction proved optimal. The developed method was evaluated with re spect to precision and limits of detection (LOD). The relative standard dev iations of replicate ASE-SPME determinations (n = 5) were in the range of 4 -24%. LOD values between I and 10 mug/kg were achieved with the exception o f DDT and DDE (40 mug/kg). Using SBSE, the LOD of these compounds could be improved (2 and 5 mug/kg). The main advantages of this method are the avoid ance of cleanup and concentration procedures as well as the significant red uction of the required volume of organic solvents. The described method was applied to the determination of the pollutants in strawberry samples colle cted from different allotment gardens in a potentially polluted area, the B itterfeld-Wolfen region (Germany).