An Enzyme-Linked Immunosorbent Assay for Detection of Linear Alkylbenzene Sulfonate: Development and Field Studies

An accurate immunoassay system was developed for the quantitative analysis of linear alkylbenzene sulfonates (LAS), the most widely used anionic surfactants among domestic detergents. To generate LAS-specific monoclonal antibodies (mAb), hybridoma cells were produced by the fusion of mouse myeloma cells and spleen cells from mice immunized with sulfophenyl-5-valeric acid coupled to bovine serum albumin. After screening using a competitive enzyme-linked immunosorbent assay (ELISA), a mAb with a high binding affinity for LAS was selected and used in the development of a sensitive competitive direct ELISA. The detection range is between 20 and 500 ppb LAS. The ELISA assay was optimized and validated by comparison with conventional methods for the analysis of LAS and anionic surfactants, such as high-performance liquid chromatog raphy (HPLC) and methylene blue active substances (MBAS) methods, in river samples. The correlation coef ficients between the assay values obtained using the ELISA and the HPLC and MBAS were 0.98 and 0.97, respectively. It is anticipated that this immunoassay system will be a useful monitoring technique for the detection of LAS in environmental water samples.