Determination of bentazone, dichlorprop, and MCPA in different soils by sodium hydroxide extraction in combination with solid-phase preconcentration

A method for the extraction of bentazone, dichlorprop, and MCPA in three se lected Norwegian soils of different textures is described. Initially three different extraction methods were tested on one soil type. All methods gave recoveries > 80% for the pesticide mixture, but extraction with sodium hyd roxide in combination with solid-phase preconcentration was used for furthe r recovery tests with soils of different properties spiked at four herbicid e concentration levels (0.001-10 mug/g of wet soil). The method was rapid a nd easy and required a minimum of organic solvents. The recoveries were in the range of 82-109, 80-123, and 45-91% for the soils containing 1.4 (Hole) , 2.5 (Kroer), and 37.8% (Froland) organic carbon, respectively. Limits of quantification using GC-MS were 0.0003 mug/g of wet soil for bentazone and 0.0001 mug/g of wet soil for both dichlorprop and MCPA.