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

A hapten-heterologous indirect ELISA system has been devised for the detection of pyrene and other polyaromatic hydrocarbons (PAHs). A polyclonal antibody previously raised against a conjugate of 1-pyrenebutyric acid (6) and a novel coating antigen based on an aldoxyme derivative of 1-pyrenecarboxaldehyde (1) were used. The new ELISA format using different concentrations of the coating antigen allowed serum dilutions in the range of 1 : 300,000. Pyrene 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 μg ml−1, respectively. Depending on assay conditions, lower limits of detection fell into the range of 0.5–4 ng ml−1 of pyrene. The novel immunoassay was compared to the assay format utilizing a diazo conjugate of 1-aminopyrene (4) as a coating antigen. The two methods appear to be comparable in sensitivity and working concentration range of the analyte, but the present assay format allows higher serum dilutions and milder coating conditions. The cross-reactivity pattern of the two assay formats appear to be somewhat similar, but display characteristic differences: in the novel format, the pyrene antiserum shows lower cross-reactivity with structurally related PAH compounds.