PILOT SURVEY FOR ATRAZINE AND TOTAL CHLOROTRIAZINES IN ESTUARINE WATERS USING MAGNETIC PARTICLE BASED IMMUNOASSAY AND GAS-CHROMATOGRAPHY NITROGEN PHOSPHORUS DETECTION/

The determination of atrazine in estuarine waters in the presence of t he common cross-reactants deethylatrazine, deisopropylstrazine, and si mazine has been investigated using direct rapid pesticide immunodetect ion (RaPID) magnetic particle-based solid-phase ELISA. Different param eters such as least detectable dose, 50% inhibition concentration, and percentage of cross-reactivity, determined by estimating the amount o f compound required to displace 50% of the enzyme conjugate to the amo unt of atrazine, were calculated. Estuarine water samples containing v arious chlorotriazine herbicides from a pilot monitoring program (with levels varying from 0.008 to 0.326 mu g/L) were compared by using the RaPID assay and gas chromatography-nitrogen/phosphorus detection (GC- NPD). Both analytical methods showed good correlation for atrazine and total chlorotriazines for most of the estuarine water samples analyze d. Gas chromatography/mass spectrometry (GC/MS) was used for confirmat ion purposes, and false positives were detected.