Determination of 10 particle-associated multiclass polar and semi-polar pesticides from small streams using accelerated solvent extraction.

A new analytical method using accelerated solvent extraction was developed for the determination of 10 particle-associated polar and semipolar pesticides. In addition, six deuterated analogues of the target compounds were evaluated as internal standards. The method yielded acceptable accuracy (73-103% recovery) and precision (<25% relative standard deviation) for eight compounds. Using size exclusion chromatography (SEC) as cleanup step resulted in higher recoveries compared to solid phase extraction (SPE) cleanup. Deuterated standards with 10 or more deuterium atoms performed well as internal standards concerning similar recovery and correlation with the target analytes. The method was employed to extract particle-associated pesticides from 16 streams located in an area with intense agriculture in France. Acetochlor, pirimicarb, tebuconazole, fenpropidin, alpha-endosulfan and chlorfenvinphos were detected at concentrations up to 1 mg kg(-1) dry weight. A comparison with aquatic toxicity data indicated potential risk to the benthic fauna exposed to these concentrations of pirimicarb, alpha-endosulfan and chlorfenvinphos. We suggest that the method presented here be used for the extraction and quantitation of particle-associated polar pesticides.

Identification of toxic products of anthracene photomodification in simulated sunlight.

Currently, the evidence of a rapid photomodification of anthracene under sunlight resulting in enhanced toxicity exists; however, the chemical causes of toxicity are still unknown. The present study aimed at filling this gap by irradiation of an anthracene suspension with simulated sunlight and subsequent effect-directed fractionation and analysis of toxic products with respect to the inhibition of bacterial energy metabolism of Vibrio fischeri, reproduction of the green algae Scenedesmus vacuolatus, and genotoxicity in the umuC test. Algal toxicity of anthracene was hardly modified by irradiation prior to testing and distributed over all fractions with emphasis on the fractions containing anthracene-9,10-dione and a photometabolite suggested to be 10-hydroxyanthrone. Bacterial toxicity and genotoxicity in contrast emerged only when anthracene was irradiated. Anthracene-1,4-dione, a so-far-unknown trace photometabolite, was identified as a very potent toxicant dominating the toxicity of photomodified anthracene to V. fischeri. In genotoxic fractions, 1-hydroxyanthracene-9,10-dione and 1,4-dihydroxyanthracene-9,10-dione were identified and confirmed as genotoxicants. The results stress the potential of effect-directed analysis approaches in contrast to mere chemical analysis in studies aiming at toxicologically relevant photomodified substances.