Detection of the Antimicrobial Triclosan in Environmental Samples by Immunoassay.

A sensitive, competitive enzyme-linked immunosorbent assay (ELISA) for the detection of the antimicrobial triclosan (TCS; 2,4,4′-trichloro-2′-hydroxydiphenyl ether) was developed. Novel immunizing haptens were synthesized by derivatizing at the 4-Cl position of the TCS molecule. Compounds derived from substitutions at 4′-Cl and that replaced the 2′-OH with a Cl atom were designed as unique coating antigen haptens. Polyclonal rabbit antisera were screened against the coating antigen library to identify combinations of immunoreagents resulting in the most sensitive assays. The most sensitive assay identified was one utilizing antiserum no. 1155 and a heterologous competitive hapten, where the 2′-OH group was substituted with a Cl atom. An IC50 value and the detection range for TCS in assay buffer were 1.19 and 0.21–6.71 μg/L, respectively. The assay was selective for TCS, providing low cross-reactivity (<5%) to the major metabolites of TCS and to brominated diphenyl ether-47. A second assay utilizing a comp...