Determination of organochlorine pesticides and chlorobenzenes in fruit and vegetables using subcritical water extraction combined with sorptive enrichment and CGC-MS

A scheme has been developed for the determination of hexachlorocyclohexanes, DDX compounds and chlorobenzenes in fruit and vegetable samples (strawberries, apples, kohlrabi, lettuce and tomatoes). The method is based on the accelerated solvent extraction (ASE) with water or water-acetone mixtures followed by solid-phase microextraction (SPME) and stir bar sorptive extraction (SBSE), and subsequent thermodesorption-CGC-MS. Using spiked water and strawberry samples, important SPME and SBSE as well as ASE parameters were optimized. The ASE-SPME and ASE-SBSE procedures developed and optimized for the matrix strawberry could be applied successfully to other fruits and vegetables (apples, kohlrabi, lettuce and tomatoes). Both procedures were applied to the different matrices and evaluated. The relative standard deviations (n = 5) for the analytes in different plant materials were in the range of 4 to 31% for both procedures. For the ASE-SPME procedure detection limits (LOD) between < 0.5 and 6 <mu>g kg(-1) were achieved except for the DDX compounds (up to 40 mug kg(-1)). Using the ASE-SBSE, the LOD values for most of the analytes could be significantly improved. These procedures were applied to the determination of chlorobenzenes, HCH isomers and DDX compounds in strawberry, apple, kohlrabi, lettuce and tomato samples taken from 12 allotment gardens in a potentially polluted region of East Germany.