Selected chloro and bromo derivatives of triclosan--syntheses and their occurrence in Canadian sewage and biosolid samples

Rapid capture and SERS detection of triclosan using a silver nanoparticle core - protein satellite substrate

Triclosan (TCS) is a synthetic antimicrobial compound that has been widely used in consumer products. However, increasing evidence suggests adverse effects of TCS to human health and environment, raising great public concerns. The existing methods for detecting TCS are limited to time-consuming and complicated procedure. Here, we developed a rapid method for capture and detection of TCS using surface-enhanced Raman spectroscopy (SERS) based on a silver nanoparticle (Ag NP) core - protein satellite nanostructure. Bovine serum albumin (BSA) assembled on Ag NPs as satellites configuration could anchor a large number of TCS molecules close to the surface of Ag NPs, producing amplified SERS signals. As low as 50 nM TCS standard was successfully detected within 30 min. We also demonstrated its capability for TCS detection in pond water. The developed SERS method holds a great promise for rapid screening of TCS in environmental and food samples.

Occurrence and removal of triclosan in Canadian wastewater systems

Triclosan (TCS) is an antimicrobial agent used in many personal care and cleaning products. It has been detected in most environmental compartments and the main entry pathway is wastewater effluents and biosolids. TCS was analyzed in 300 samples of raw influent, final effluent, and biosolids from 13 wastewater treatment plants (WWTPs) across Canada representing five types of typical wastewater treatment systems. TCS was almost always detected in influent (median 1480 ng/L), effluent (median 107 ng/L), and biosolids (median 8000 ng/g dry weight) samples. Removals of TCS from lagoons as well as secondary and advanced treatment facilities were significantly higher than primary treatment facilities (p < 0.001). TCS removal was strongly correlated with organic nitrogen removal. TCS removals at most lagoons and plants that use biological treatment were higher during summer compared with winter. However, no seasonal or temperature effects were observed at the two primary facilities, likely due to the absence of biological activity. Aerobically digested solids contained the lowest levels (median 555 ng/g) while anaerobically digested primary solids contained the highest levels of TCS (median 22,700 ng/g). The results of this large comprehensive study demonstrate that TCS is consistently present in wastewater and biosolids at relatively high concentrations and that removal from wastewater and levels in biosolids are strongly influenced by the wastewater and solids treatment types.

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 competitive hapten containing Br instead of Cl substitutions was broadly selective for both brominated and chlorinated diphenylethers. Using the most sensitive assay combination, we measured TCS concentrations in water samples following dilution. Biosolid samples were analyzed following the dilution of a simple solvent extract. The immunoassay results were similar to those determined by LC-MS/MS. This immunoassay can be used as a rapid and convenient tool to screen for human and environmental exposure.

Bisphenol-A removal in various wastewater treatment processes: operational conditions, mass balance, and optimization

Bisphenol-A (BPA) was analyzed in 499 liquid and 347 solid samples collected from twenty-five wastewater treatment plants (WWTPs) to investigate parameters affecting BPA occurrence, removal, and fate. Lagoons, chemically-assisted primary treatment, secondary treatment, and advanced treatment processes were included. Median BPA concentrations in influent and final effluent were 400 ng/L and 150 ng/L, respectively. Median removal efficiencies ranged from 1 to 77%. Respective median BPA levels in primary sludge, secondary biological sludge, and biosolids were 230, 260, and 460 ng/g with digested biosolids having the highest concentrations. The biological aerated filter and membrane bioreactor processes showed the best performance, while chemically-assisted primary treatment achieved the lowest removal. Biodegradation and sorption contributing to BPA removal were influenced by operational conditions: hydraulic retention time (HRT), solids retention time (SRT), and mixed liquor suspended solids (MLSS). The influence of HRT, SRT, and MLSS in the bioreactor was stronger during cold temperatures. In order to achieve above 80% removal, the required conditions for HRT, SRT, and MLSS were 13 h, 7 days, and 1600 mg/L during summer (median temperature 19 °C) and 13 h, 17 days, and 5300 mg/L during winter (median temperature 10 °C); indicating that longer SRT and higher MLSS were needed during winter. BPA's sorption tendency to sludge was strongly influenced by the degree of nitrification and HRT.