Submitted to: Analytical and Bioanalytical Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/25/2011
Publication Date: 8/6/2011
Citation: Wang, J., Li, H., Shelver, W.L., Wang, Z., Li, Q.X., Li, J., Xu, T. 2011. Development of a monoclonal antibody-based, congener-specific and solvent-tolerable direct enzyme-linked immunosorbgent assay for the detection of 2,2',4,4'-tetrabromodiphenyl ether in environmental samples. Analytical and Bioanalytical Chemistry. 401:2249-2258. Interpretive Summary: Polybrominated diphenyl ethers (PBDEs) are a group of chemicals that were widely used in plastics, polyurethane foam, and electronic equipment as fire retardants. Because of their persistence, PBDE congeners have been found in various sources in the environment and food web. Scientists are searching for new and improved methods to measure PBDEs in environmental and biological samples quickly and accurately. Instrumental methods using chromatography combined with mass spectrometry are most commonly used for the detection of PBDEs. Although sensitive and specific, these methods are time-consuming, expensive, and limited to a laboratory environment. Alternatively, immunoassays are rapid, sensitive, and selective and have been used to determine trace chemicals in a variety of matrices. We have produced a monoclonal antibody that is highly specific to BDE-47 (the most commonly found and persistent BDE in the environment and food chain) as well as being highly tolerable to organic solvent DMSO. A highly specific (< 6% cross-reactivity) and sensitive (< 100 parts per trillion) immunoassay was developed using this antibody. The assay can tolerate up to 50% DMSO in the assay buffer solution. Satisfactory recoveries of BDE-47 from spiked soil, sediment and house dust samples by the immunoassay were obtained with acceptable precision. This assay was finally applied to the analysis of real world samples in which BDE-47 was found in a wide range of concentration in different sample types.
Technical Abstract: A sensitive direct enzyme-linked immunosorbent assay (ELISA) for the detection of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in environmental samples was developed. A hapten mimicking the whole structure of BDE-47 was synthesized by introducing a butyric acid spacer to 5-hydroxy-BDE-47 and coupled to keyhole limpet hemocyanin (KLH) to form an immunogen for the production of monoclonal antibody (Mab) against BDE-47. The most sensitive direct ELISA was formatted with a Mab, designated as 4F2, in combination with 5-(2,4-dibromophenoxy) pentanoic acid-peroxidase as a tracer. The inhibition half-maximum concentrations (IC50) and limit of detection (LOD) were 1.4 ± 0.05 ng mL-1 and 0.1 ng mL-1, respectively. Cross-reactivity values of the ELISA with the tested BDE congeners and metabolites were = 5.8%. This assay was used to determine BDE-47 in soil, sediment and house dust samples after ultrasonic extraction, simple cleanup and concentration steps. This assay was validated by comparison with a gas chromatography with mass spectrometry (GC-MS) and then applied to real world samples. The average recoveries of BDE-47 by ELISA and GC-MS were in a range of 77-125% and 80-116%, respectively. BDE-47 values measured in the agricultural soil, sediment and house dust samples ranged from undetectable level to 492 ng g-1.