Determination of organophosphate and carbamate pesticides in spiked samples of tap water and fruit juices by a biosensor with photothermal detection

The determination of organophosphate (paraoxon, chlorpyrifos, diazinon) and carbamate (carbaryl, carbofuran) pesticides in spiked drinking water and fruit juices was carried out using a photothermal biosensor. The biosensor consists of a cartridge containing immobilised enzyme acetylcholinesterase (AChE) placed in a flow-injection analysis (FIA) manifold and a photothermal detector based on thermal lens spectrometry. With this approach, 0.2 ng/ml of paraoxon can be detected in less than 15 min. Limits of detection for other organophosphate (chlorpyrifos, diazinon) and carbamate (carbaryl, carbofuran) pesticides varied, depending on their antiacetylcholinesterase (AntiAChE) toxicity, from 1 ng/ml to 4 mu g/ml. The biosensor was used for the direct detection of pesticides in spiked tap water and fruit juices without any pretreatment steps. In these cases, the LOD3 sigma of 1.5, 2.8 and 4 ng/ml paraoxon in tap water, orange juice and apple juice were obtained, respectively. (C) 1999 Elsevier Science S.A. All rights reserved.