Development of an immunochromatographic assay for the rapid detection of chlorpyrifos-methyl in water samples

A rapid (less than 10 min), qualitative and semi-quantitative immunochromatography using colloidal gold-antibody probe was successfully developed and applied in determination of chlorpyrifos-methyl (a wide-spectrum organophosphorus pesticide) in water samples The qualitative detection limit of chlorpyrifos-methyl was determined as 0 6 mu g ml(-1) by using immunochromatography. In the semi-quantitative experiment, the detection results of chlorpyrifos-methyl were scanned by a membrane strip reader, and a detection curve representing the scanned data average was obtained. After conversion, it was observed that in the range of 50 - 12,150 ng ml(-1), the graph between logit(B/B-0)and logarithm of concentration of chlorpyrifos-methyl was linear, from which, the regression equation (y = 2 5229x + 7 5951, R-2 = 0 9889) and IC50 value (1024.39 ng ml(-1)) was obtained, respectively Meanwhile, the detection limit was calculated as 132 91 ng ml(-1) by the extrapolation of B-0 - 2SD In addition, the cross-reactivines were less than 1% with tested analog compounds and regarded as negligible The recoveries obtained by standard chlorpyrifos-methyl addition to water samples were 102 5-107 6% Overall, to our knowledge, this is the first report of qualitative and semi-quantitative detection of chlorpyrifos-methyl by immunochromatography (C) 2010 Elsevier B V All rights reserved.