A modified enzyme-linked immunosorbent assay (ELISA) for polyaromatic hydrocarbons

A hapten-heterologous indirect ELISA system has been devised for the detect ion of pyrene and other polyaromatic hydrocarbons (PAHs). A polyclonal anti body previously raised against a conjugate of 1-pyrenebutyric acid (6) and a novel coating antigen based on an aldoxyme derivative of 1-pyrenecarboxal dehyde (1) were used. The new ELISA format using different concentrations o f the coating antigen allowed serum dilutions in the range of 1 :300,000. P yrene was detected with an IC50 value of 2.2 +/- 0.6 and 48.8 +/- 1.4 ng ml (-1) for coating antigen concentrations of 0.1 and 0.5 mu g ml(-1), respect ively. Depending on assay conditions, lower limits of detection fell into t he range of 0.5-4 ng ml(-1) of pyrene. The novel immunoassay was compared to the assay format utilizing a diazo co njugate of l-aminopyrene (4) as a coating antigen. The two methods appear t o be comparable in sensitivity and working concentration range of the analy te, but the present assay format allows higher serum dilutions and milder c oating conditions. The cross-reactivity pattern of the two assay formats ap pear to be somewhat similar, but display characteristic differences: in the novel format, the pyrene antiserum shows lower cross-reactivity with struc turally related PAH compounds. (C) 1999 Elsevier Science B.V. All rights re served.