An Adsorption Procedure for Determining the Level of Organophosphorus Pesticide Residues in Pond Water

Abstract

Abstract A procedure for the accumulation of phosphorus-containing degradation products of organophosphorus pesticides from water by elution of ion-associates of dialkylphosphorus anions with tetraphenylarsonium cation adsorbed onto an activated carbon micro-column is described. Using a 50cm3 sample volume at a concentration of 1 μcm−3 the average accumulation recoveries (%±S.D.) were 81±11 and 91±8 for diethyl and dimethyl phosphorodithioates, 69±10 and 66±10 for the corresponding phosphorothioates and 33±13 and 13±6 for the analogous phosphates. A decrease in these values was caused by the presence of common inorganic anions and at lower concentrations of the analysed species. At a detection limit of 20 ng cm−3 the recovery was 20–30%. Despite of low accumulation recoveries the minimum detectable concentration of these anions was decreased below 0.1 ng cm−3 by handling 1 dm3 sample volumes. The procedure was applied for the analysis of dialkyl phosphorothioates and dialkyl phosphorodithioates in the water from, three ponds located in an apple orchard before and after seasonal application of organophosphorus pesticides. Key Words: Organophosphorus pesticide residuesdialkyl phosphorothioatesdialkyl phosphorodithioatesactivated carbonwater analysis