A High-Throughput Screening Immunochemical Protocol for Biological Exposure Assessment of Chlorophenols in Urine Samples

This chapter presents a high-throughput screening (HTS) immunochemical procedure suitable for processing and analyzing simultaneously multiple urine samples. The method presented here is addressed to assess the level of exposure of the population to certain organochlorine substances (i.e., dioxins, lindane, hexachlorobenzene, chlorophenols, etc.) by analyzing the concentration of chlorophenols in urine. The procedure consists mainly of three steps. First, the urine samples are treated in basic media to hydrolyze the glucuronide and sulfate conjugates of the chlorophenols. Next, the free chlorophenol fractions are selectively isolated by immunosorbents (ISs), specially prepared for this purpose. Finally, this fraction is quantified with a microplate ELISA (enzyme-linked immunosorbent assay). All solid-phase extraction (SPE) and analytical methods can be performed on a 96-plate configuration. The HTS-IS-ELISA procedure has been proved to be efficient, consistent, and reliable. The main advantages are the simplicity, the high sample throughput capabilities, and the small urine sample volumes required for each assay. With the present analytical protocol, quantitation can be accurately performed within 0.3 and 30 �g/L 2,4,6-trichlorophenol. About 100 samples per day can be processed with inter- and intraassay precision (%CV) below 20%, except when measurements take place at the level of the ELISA limit of detection. A protocol such as that presented here may be generally applied in environmental or biological monitoring programs for which many complex samples have to be screened as far as antibodies with the necessary specificity and affinity are available.