Determination of triclosan in foodstuffs

The environmentally friendly approaches based on the heterojunction interface of the LaFeO3/Fe2O3@g-C3N4 composite for the disposable and laboratory sensing of triclosan

Triclosan (TCS) is a polychlorinated phenoxy phenol (PCPPs) used as a disinfectant and a broad-spectrum antibacterial and antifungal agent in personal hygiene products. TCS easily forms diphenyl ethers and dioxins, which are persistent organic pollutants. This work used a double approach for the TSC sensing: a) screen-printed (SPE) electrochemical platform for on-site application, modified with lanthanum iron oxide and graphitic carbon nitride composite (LaFeO₃/Fe₂O₃@g-C₃N₄/SPE); and b) carbon paste electrode (CPE), modified with the same material and used in laboratory conditions. Linear range from 0.1 μM to 10 μM, the limit of detection (LOD) of 29 nM and the limit of quantification (LOQ) of 91 nM were obtained for CP electrode in BRBS pH 8. SPE showed the best analytical parameters in BRBS at pH 3, with a linear range from 0.3 μM to 7 μM, LOD of 0.09 μM and LOQ of 0.28 μM. Furthermore, the influence of potential interferents was investigated and proven to be negligible. Determination of TSC was performed to estimate the environmental impact of this compound as well as the practical usefulness of the proposed sensor in the real sample analysis, confirmed with a HPLC analysis.

Smartphone-based colorimetric determination of triclosan in aqueoussamples after ultrasound assisted-dispersive liquid-liquid microextraction under optimized response surface method conditions

In the present study, a simple and low cost methodology based on ultrasonic assisted-dispersive liquid-liquid microextraction (UA-DLLME) followed by smartphone-based colorimetric measurement was introduced for the separation and determination of Triclosan (TCS) from contaminated waters. This method is based on the formation of an azo compound from the alkaline reaction of TCS with a diazonium ion, resulting from the reaction of sodium nitrite and p-sulfanilic acid in an acidic medium. The orange-brown color product was extracted into a low volume of organic phase by UA-DLLME method and RGB values were recorded with free Android app Color Grab. The effective parameters in this procedure, namely solution pH, p-sulfanilic acid and nitrite concentration, reaction time and volume of the extraction solvent were investigated and optimized by response surface methodology (RSM) based on a Box-Behnken design (BBD) model. Under optimum conditions, the calibration graph was linear in the range of 3.0 and 200 μg L^-1 of TCS. The limit of detection (LOD) and limit of quantification (LOQ) were 0.8 and 2.7 μg L^-1, respectively. The proposed method was successfullyused for the analyses of triclosan in several water and wastewater samples and satisfactory results were obtained.

Critical review on the mechanistic photolytic and photocatalytic degradation of triclosan

The environmentally extended presence of triclosan, TCS, component of many pharmaceutical and personal care products, and its known persistent character have awoke the scientific and social concern leading to the study of effective remediation techniques. Advanced oxidation techniques stand out for the effectiveness in degrading many persistent compounds, and as a result, they have been addressed by many researchers. However, the powerful oxidation media might lead to the formation of undesirable by-products, concern that has also been widely addressed. With regard to the presence of TCS, photolytic and photocatalytic processes provide a very effective degradation yield and rate, with a large number of reports addressing its removal from different environmental matrices. But currently, there is no clear understanding of the mechanisms involved and the routes responsible for the formation of degradation products. Thus, this work presents an exhaustive and critical analysis of the state of the art related to the photo-degradation of TCS, with special focus on the formation of oxidation by-products, on the phenomena responsible and on the influence of operation variables. This report aims at offering valuable information to researchers dealing with this environmentally relevant problem.

PCDD/Fs traceability during triclosan electrochemical oxidation

5-Chloro-2-(2,4-dichlorophenoxy)phenol (TCS) is a persistent organic pollutant (POP) widely used in different consumer goods. Its recalcitrant nature demands the application of effective remediation technologies in order to avoid the negative environmental impact associated to the discharge of contaminated waters. Although advanced oxidation technologies have been considered the best alternative to destroy bio-recalcitrant compounds, the likely formation of high toxicity byproducts must be analysed before large-scale deployment. In this work, we aim to trace the presence of chlorinated compounds during the electro-oxidation of aqueous TCS samples. First, we analyze the influence of the initial concentration of TCS on the toxicity of the oxidation medium expressed by the International-Toxicity Equivalency Factor (I-TEF); second, we have detected the formation of intermediate organo-chlorinated compounds by GC-MS supported by HPLC and finally, we have quantified the concentration of highly-polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) by HRGC-HRMS within the oxidation treatment. In those samples where TCS had been completely degraded the concentration of PCDD/Fs showed a high increase, especially when NaCl was used as electrolyte, with the initial concentration of TCS. Under these conditions the I-TEF achieved values up to 3.8 × 10² pg L^-1.

Spectrophotometric determination of triclosan based on diazotization reaction: response surface optimization using Box-Behnken design

A spectrophotometric method based on diazotization of aniline with triclosan has been developed for the determination of triclosan in water samples. The diazotization process involves two steps: (1) reaction of aniline with sodium nitrite in an acidic medium to form diazonium ion and (2) reaction of diazonium ion with triclosan to form a yellowish-orange azo compound in an alkaline medium. The resulting yellowish-orange product has a maximum absorption at 352 nm which allows the determination of triclosan in aqueous solution in the linear concentration range of 0.1-3.0 μM with R² = 0.998. The concentration of hydrochloric acid, sodium nitrite, and aniline was optimized for diazotization reaction to achieve good spectrophotometric determination of triclosan. The optimization of experimental conditions for spectrophotometric determination of triclosan in terms of concentration of sodium nitrite, hydrogen chloride and aniline was also carried out by using Box-Behnken design of response surface methodology and results obtained were in agreement with the experimentally optimized values. The proposed method was then successfully applied for analyses of triclosan content in water samples.

On the need and speed of regulating triclosan and triclocarban in the United States

The polychlorinated aromatic antimicrobials triclosan and triclocarban are in widespread use for killing microorganisms indiscriminately, rapidly, and by nonspecific action. While their utility in healthcare settings is undisputed, benefits to users of antimicrobial personal care products are few to none. Yet, these latter, high-volume uses have caused widespread contamination of the environment, wildlife, and human populations. This feature article presents a timeline of scientific evidence and regulatory actions in the U.S. concerning persistent polychlorinated biocides, showing a potential path forward to judicious and sustainable uses of synthetic antimicrobials, including the design of greener and safer next-generation alternatives.

Analytical performance of two miniaturised extraction methods for triclosan and methyltriclosan, in fish roe and surimi samples

A new and reliable miniaturised QuEChERS-based extraction method combined with a dispersive SPE cleanup procedure for extracting triclosan and methyltriclosan from fish roe and surimi samples was proposed. The effectiveness of different extraction/partition conditions for QuEChERS method was systematically investigated, and the use of acetonitrile extraction solvent and MgSO4, PSA, C18 and Florisil as cleanup reagents was recommended in the final method. Other method based on ultrasonic extraction with ethylacetate and clean-up with SPE was also evaluated for these samples. Different polymeric and silica sorbents for clean up were tested and the combination of Florisil and PSA was finally selected. The performance of these miniaturised sample preparation methods combined with GC-MS with quadrupole detection were compared. Extraction efficiency as well as cleaning effectiveness, laboriousness and speed were taken as criteria for method evaluation. Satisfactory validation parameters, such as linearity, recovery, precision and LODs and LOQs for both developed analytical methods were obtained from fish roe and surimi samples. Finally, both methods were applied to real samples. The sensitivity of the proposed methods was good enough to ensure reliable determination of target analytes at concentration levels commonly found in this kind of samples.

Simultaneous quantitation of parabens, triclosan, and methyl triclosan in indoor house dust using solid phase extraction and gas chromatography-mass spectrometry

An integrated analytical method for the simultaneous determination of five parabens (methyl-, ethyl-, propyl-, butyl-, and benzyl-), triclosan, and methyl triclosan in indoor house dust was developed based on gas chromatographic-mass spectrometric technique (GC/MS). Analytes were extracted from dust samples by sonication. After sample cleanup by solid-phase extraction (SPE), the extracts were derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) and then analyzed by gas chromatography coupled with ion trap mass spectrometry operated in multiple reaction monitoring (MRM) mode. For quantitation, isotope-labelled internal standards were used for each corresponding target analyte. Only 0.05 g of dust sample was needed for the analysis. Method detection limits ranged from 6.5 to 10 ng/g, and absolute recoveries from 74% to 92%. The developed method demonstrated good repeatability and reproducibility, with relative standard deviations (RSDs) less than 16% for all the analytes. The analytes were determined in dust samples collected using two vacuum sampling methods from 63 Canadian homes: a sample of fresh or "active" dust (FD) collected using a Pullman-Holt vacuum sampler, and a composite sample taken from the household vacuum cleaner (HD). Methyl paraben, propyl paraben, and triclosan were detected in all HD and FD samples. HD samples yielded median values for methyl paraben, propyl paraben, and triclosan of 1080, 463, and 378 ng/g, respectively, which were comparable to the FD sample medians of 1120, 618 and 571 ng/g. Ethyl paraben was detected at frequencies of 89% in FD and 73% in HD samples, with median values of 52 and 25 ng/g, respectively. Butyl paraben was detected at frequencies of 44% in FD and 75% in HD samples, with median values of <10 and 59 ng/g, respectively. Benzyl paraben and methyl triclosan were not detected in any of the samples collected by either method. Samples collected according to the fresh dust protocol agreed with the household vacuum samples 90% of the time. Widely scattered concentration levels were observed for target analytes from this preliminary set of 63 Canadian samples, which suggests a wide variability in Canadian household exposures to these chemicals.

Spectrophotometric determination of triclosan in personal care products

A spectrophotometric method for the determination of triclosan in personal care products was proposed. It was based on the reaction of sodium nitrite with p-sulfanilic acid in an acidic medium to form diazonium ion, with which triclosan further formed an azo compound in an alkaline medium. The resulting yellow colored product has a maximum absorption at 452 nm. A good linear relationship (r=0.9999) was obtained in the range of 0-30 mg L(-1) triclosan. A detection limit of 0.079 gL(-1) was achieved and the relative standard deviation was 0.24% (n=11) at 14 mg L(-1) triclosan. The proposed method has been applied to the analyses of triclosan in several personal care products and the results were in good agreement with those obtained by high-performance liquid chromatography.

Determinations and residual characteristics of triclosan in household food detergents of Taiwan

Triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether) is a widely used antibacterial agent. However, it was concerned recently that triclosan might act as an antibiotic and will cause resistant bacterial strains. Furthermore, possible formation of toxic chloroform was also reported when the triclosan contained in household dishwashing soaps reacted with the chlorinated water. To assess the associate risks from possible exposures, concentrations of triclosan in household food detergents of Taiwan were determined in this study. High performance liquid chromatography (HPLC) with UV detector at 280 nm was used to analyze the triclosan in samples. Factors that might affect the residual characteristics of triclosan from detergents on dishware and fruits, including the concentrations of detergents used, the temperature and immersion time for water before the cleaning processes, the temperatures of water used for the cleaning processes, and the materials of dishware made of, were evaluated under the orthogonal experiment design by the Taguchi method. By the analysis of variance, the orders of importance of different parameters were determined. The concentrations of triclosan detected in household food detergents were found to be 1.7 x 10(-2) -5.6 x 10(-1) (triclosan/detergent, mg g(-1)). For residual characteristics, the concentration of detergents used as well as the materials of dishware were found to be the significant factors that will affect the triclosan left on the dishware. On the other hand, the concentration of triclosan in the detergents was found to be the only factor that will affect the triclosan left on fruits. The maximum dose of triclosan exposures from the use of household food detergents in Taiwan was also estimated in the study.

Selective enzyme-linked immunosorbent assay for triclosan. Application to wastewater treatment plant effluents

A sensitive and highly selective enzyme-linked immunosorbent assay was developed for triclosan, one of the most common bactericides in personal care products, which is also considered as an emerging contaminant, given its presence in the effluents of sewage and wastewater treatment plants. From synthesized haptens, polyclonal rabbit antibodies against triclosan were raised. The best ELISA immunoassay was based on an antibody-coated format, yielding a detection limit of 0.03 microg L(-1), an I50 of 3.85 microg L(-1), and a dynamic range from 0.22 to 42.16 microg L(-1), with little or no cross-reactivity (< 10%) to similarly structured compounds, including its metabolite methyltriclosan (CR < 6%). The assay was applied as a screening method to quantify triclosan in surface water and in wastewaters. After C18 solid-phase extraction, nanogram per liter concentrations were determined in effluents of urban wastewater treatment plants. The satisfactory recoveries achieved as well as the agreement between immunochemical and chromatographic methods (GC-MS) indicate its potential for either screening or laboratory quantification.

Microwave assisted extraction followed by gas chromatography with tandem mass spectrometry for the determination of triclosan and two related chlorophenols in sludge and sediments

A procedure for the determination of 2-(2,4-dichlorophenoxy)-5-chlorophenol (Triclosan) and two possible transformation compounds, 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP), in sludge from sewage treatment plants (STP) and sediments is presented. Extraction was performed using an acetone:methanol (1:1) mixture under the action of a microwave field. The centrifuged supernatant was diluted with a NaOH aqueous solution and twice extracted with n-hexane for removing neutral and basic interferences. The aqueous layer was acidified and processed as a waste water sample. After concentration analytes were silylated and determined by gas chromatography with tandem mass spectrometry (GC-MS/MS). Influence of experimental conditions on the yield of the extraction process and on the efficiency of the further clean-up step was thoroughly evaluated. Performance of MS/MS detection in comparison to single MS is described. Under final working conditions quantification limits between 0.4 and 0.8 ng/g and recoveries from 78% to 106% were obtained. The method was applied to the analysis of several sludge and sediment samples. Only low levels of TCS were detected in some of the sediments; however, all three compounds were found in sludge samples at concentrations ranging from 7 to 316 ng/g, in the case of chlorophenols, and from 420 to 5400 ng/g, for Triclosan.