Evaluation of a magnetic particle-based ELISA for the determination of chlorpyrifos-ethyl in natural waters and soil samples

A magnetic particle-based ELISA for chlorpyrifos-ethyl was investigated in estuarine water matrices, and the results obtained were correlated with automated on-line solid phase extraction (Prospekt) followed by liquid chromatography/diode array detection. The ELISA test was evaluated before and after filtration of the particulate matter present in estuarine water with and without prior acidification. The ELISA assay was used as a first screening method for determining chlorpyrifos-ethyl in a highly contaminated soil spiked at common termicidal application rate (similar to 1000 mg/kg). The ELISA assay permitted us to distinguish soil contamination of chlorpyrifos-ethyl at 50 mg/kg in conjunction with Soxhlet extraction. Substantial saving time was achieved when compared to conventional methods, which require a cleanup step prior to chromatographic determinations.