Measurement of Triclosan in Water Using a Magnetic Particle Enzyme Immunoassay

Abstract

A sensitive magnetic particle-based immunoassay to determine triclosan [5-chloro-2-(2,4-dichlorophenoxy)phenol] in drinking water and wastewater was developed. Rabbit antiserum was produced by immunizing the rabbit with 6-[5-chloro-2-(2,4-dichlorophenoxy)phenoxy]hexanoic acid-keyhole limpet hemocyanin. Horseradish peroxidase was conjugated with 4-[3-bromo-4-(2,4-dibromophenoxy)phenoxy]butyric acid via N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). The triclosan antibody was coupled to magnetic particles via the NHS/EDC reaction. The antibodies were able to recognize some structurally related polybrominated biphenyl ethers but did not recognize various common pollutants that were less similar to the hapten. The ELISA could detect triclosan in standard solution (25% methanol/H2O v/v) at 20 ppt and its metabolite, methyl-triclosan, at 15 ppt. Water samples from different treatment stages were prepared to contain 25% methanol and analyzed directly without any sample extraction or preconcentration. The results showed that recoveries were >80% and the % CV was <10%, demonstrating the assay was both accurate and precise. Application of the triclosan ELISA to water treatment plants showed that tap water at various purification stages had low concentrations of triclosan (<20 ppt) and required an increased sample size for appropriate detection and measurement. Application of ELISA to the wastewater treatment plants (WWTP) demonstrated high concentrations of triclosan (in general, >3000 ppt in water entering the WWTP) with the levels decreasing as the water proceeded through the processing plant (<500 ppt at outflow sewage). The ELISA measurement was shown to be equivalent to the more specific GC-MS analysis on a number of wastewater treatment samples with a high degree of correlation, with the exception of a few samples with very high triclosan concentrations (>5000 ppt). Measurement of methyl-triclosan (in WWTP) using GC-MS demonstrated the levels of this compound to be low. In summary, a rapid, sensitive, accurate, and precise magnetic particle-based immunoassay has been developed for triclosan analysis, which can serve as a cost-effective monitoring tool for various water samples.

Detection of the Antimicrobial Triclosan in Environmental Samples by Immunoassay

“…The LOD in buffer was 0.1 μg/L, the IC 10 value (Figure 2). This assay is comparable in sensitivity to the formats reported earlier that exhibited IC 50 values for TCS of 3.85 μg/L 19 and 0.25 μg/L 18 …”

“…19 The antibody generated against hapten T1 where the -OH group of TCS was alkylated to - OCH 2 (CH 2 ) 2 -COOH, highly recognized methyl TCS and BDE-47 and showed less specificity to TCS due to the lack of H-bonding donation, which is consistent with earlier findings using a similar immunizing hapten conjugated through the hydroxyl. 18 …”

“…Immunoassays for TCS detection have been developed previously 18,19 . However, the formats in which these have been developed require a relatively large amount of primary antibody reagent because the solid support (e.g.…”

Selective Enzyme-Linked Immunosorbent Assay for Triclosan. Application to Wastewater Treatment Plant Effluents

“…As it has been described (20), filtered and nonfiltered wastewater samples display different results; up to 63% triclosan may be in the suspended matter. Filtering greatly reduced the amount of triclosan in the samples, due to removal of the bounded triclosan.…”

“…Another strategy was to obtain an ether, ended in a carboxylic acid, following the Williamson ether synthesis procedure (20). Due to phenol acidity, it is easy to generate the corresponding alkoxide with potassium carbonate; the subsequent reaction with methyl bromoacetate, followed by ester hydrolysis, leads to the acid Tr2 in good yield ( Figure 1).…”