Development and optimization of an indirect enzyme-linked immunosorbent assay for 4-nitrophenol. Application to the analysis of certified water samples

A polyclonal antibody-based enzyme-linked immunosorbent assay (ELISA) for t he detection of 4-nitrophenol (4-NP) was developed, optimized and validated for the analysis of this polar compound in water samples. The concentratio ns of the immunoreagents were selected to provide the highest sensitivity o n an indirect ELISA format. Moreover, the influence of several physico-chem ical parameters, such as incubation time, ionic strength, detergent concent ration and pH were also studied. The IC50 and limit of detection (LOD) of t he optimized assay As34/3-BSA (antiserum 34 and hapten 3 conjugated to bovi ne serum albumin) were 9.32 and 0.61 mu g 1(-1), respectively. The specific ity of this immunoassay was also evaluated by using eleven phenolic compoun ds, four different structurally related organophosphorus pesticides and a s urfactant. Two binds of sample matrices (Milli-Q and river water) were eval uated for possible interferences. A good correlation between the analysis b y conventional techniques and by immunoassay was obtained, when five certif ied water samples were analyzed. (C) 1999 Elsevier Science B.V. All rights reserved.