Development of a selective enzyme-linked immunosorbent assay for 1-naphthol - The major metabolite of carbaryl (1-naphthyl N-methylcarbamate)

A selective enzyme-linked immunosorbent assay for 1-naphthol was developed. Eight rabbits were immunized with either [(5-hydroxy-2-naphthylenyl)oxy]acetic acid (2b)-BSA, [(5-hydroxy-1-naphthylenyl)oxy]acetic acid (4)-BSA, or 5-hydroxy-2-naphthoic acid (7)-KLH, and all sera were screened against 14 different coating antigens. From this screening procedure, five assays could be developed, using two 7-KLH antisera, 3907 and 3909. The assay with the least interference and the best reliability (7-KLH antiserum 3907, 1:9000, and coating antigen 2b-BSA, 1.5 μg/mL) was further optimized and characterized. It showed an I₅₀ value of about 72 μg/L, with a range of detection from 10 to 1000 μg/L. There was no cross-reactivity with carbaryl, which makes this assay very suitable for the selective detection of 1-naphthol, for example, in undiluted human urine and in soil extract. The assay was tested in organic solvents and showed a tolerance of at least 10% solvent (acetone, acetonitrile, methanol).