Approaches for the Simultaneous Extraction of Tetrabromobisphenol A, Tetrachlorobisphenol A, and Related Phenolic Compounds from Sewage Sludge and Sediment Samples Based on Matrix Solid-Phase Dispersion

A simple and green offline-online capillary electrophoresis stacking strategy for the simultaneous determination of hydrophobic compounds in complicated samples using sodium dodecyl sulfate as the solubilizer and pseudophase

BACKGROUND

Capillary electrophoresis is a powerful analytical method featured with high separation efficiency, minimal sample requirements, and reduced organic solvents consumption. However, its low sensitivity hinders its wide application in determination of trace analytes especially for the weakly ionized hydrophobic compounds. Offline and Online capillary electrophoresis stacking methods are more favored to enhance detection sensitivity of analytes. The determination of two sesquiterpenes and an alkaloid from the dried root of Lindera aggregata merged as an example for developing a simple, sensitive and green method for the simultaneous determination of two hydrophobic compounds in complicated matrix samples.

RESULTS

An offline-online capillary electrophoresis stacking strategy by integrating micro matrix solid phase dispersion with field-amplified sample stacking and micelle to cyclodextrin stacking has been developed for the simultaneous determination of dehydrocostus lactone, linderane, norisoboldine in complex matrices. The optimized parameters were set at 65 mM sodium dihydrogen phosphate, 35 % methanol, 180 s for sample injection and 210 s for cyclodextrin injection, 20 mM sodium dodecyl sulfate of sample matrix for online stacking; 1:1 sample to MCM-48, 180 s grinding time, and 1000 μL of 20 mM sodium dodecyl sulfate elution for offline procedure. Under the optimum conditions, the method showed good linearity with correlation coefficients (R2 ≥ 0.9927), low limits of detection within the range of 25-50 ng mL-1, satisfactory repeatability and reproducibility below 3.98 %, and acceptable recoveries between 94 % and 97 %. The developed method was successfully applied to two real samples, the root of L. aggregata and rat feces.

SIGNIFICANCE

Sodium dodecyl sulfate is firstly used as an eluent in micro matrix solid phase dispersion and plays a dual role throughout the analytical procedure, including extraction solvent in sample preparation and micelle pseudophase during online stacking. It brings great procedure convenience to the method. The sensitivity of this method can improve up to 1283-folds compared with the normal mode. Moreover, the overall strategy indicates satisfied green potential evaluated by greenness assessment tools.

Developmental toxicity of TCBPA on the nervous and cardiovascular systems of zebrafish (Danio rerio): A combination of transcriptomic and metabolomics

Tetrachlorobisphenol A (TCBPA), a widely used halogenated flame retardant, is frequently detected in environmental compartments and human samples. However, unknown developmental toxicity and mechanisms limit the entire understanding of its effects. In this study, zebrafish (Danio rerio) embryos were exposed to various concentrations of TCBPA while a combination of transcriptomics, behavioral and biochemical analyzes as well as metabolomics were applied to decipher its toxic effects and the potential mechanisms. We found that TCBPA could interfere with nervous and cardiovascular development through focal adhesion and extracellular matrix-receptor (ECM-receptor) interaction pathways through transcriptomic analysis. Behavioral and biochemical analysis results indicated abnormal swimming behavior of zebrafish larvae. Morphological observations revealed that TCBPA could cause the loss of head blood vessels. Metabolomic analysis showed that arginine-related metabolic pathways were one of the main pathways leading to TCBPA developmental toxicity. Our study demonstrated that by using omics, TCBPA was shown to have neurological and cardiovascular developmental toxicity and the underlying mechanisms were uncovered and major pathways identified.

Bisphenols Promote the Pheromone-Responsive Plasmid-Mediated Conjugative Transfer of Antibiotic Resistance Genes in Enterococcus faecalis

The enrichment and spread of antibiotic resistance genes (ARGs) induced by environmental chemical pollution further exacerbated the threat to human health and ecological safety. Several compounds are known to induce R plasmid-mediated conjugation through inducing reactive oxygen species (ROS), increasing cell membrane permeability, enhancing regulatory genes expression, and so forth. Up to now, there has been no substantial breakthrough in the studies of models and related mechanisms. Here, we established a new conjugation model using pheromone-responsive plasmid pCF10 and confirmed that five kinds of bisphenols (BPs) at environmentally relevant concentrations could significantly promote the conjugation of ARGs mediated by plasmid pCF10 in E. faecalis by up to 4.5-fold compared with untreated cells. Using qPCR, gene knockout and UHPLC, we explored the mechanisms behind this phenomenon using bisphenol A (BPA) as a model of BPs and demonstrated that BPA could upregulate the expression of pheromone, promote bacterial aggregation, and even directly activate conjugation as a pheromone instead of producing ROS and enhancing cell membrane permeability. Interestingly, the result of mathematical analysis showed that the pheromone effect of most BPs is more potent than that of synthetic pheromone cCF10. These findings provide new insight into the environmental behavior and biological effect of BPs and provided new method and theory to study on enrichment and spread of ARGs induced by environmental chemical pollution.

Cost-Effective and High-Reliability Analytical Approach for Multitoxin Screening in Bivalve Mollusks by Liquid Chromatography Coupled to Tandem Mass Spectrometry

A fast, less expensive, analytical approach with high metrologic reliability was developed to assist an official program for 21 marine biotoxins, monitoring in bivalve mollusks. The simultaneous analysis of lipophilic and hydrophilic marine biotoxins was achieved using a sample preparation protocol based on solid-liquid extraction and low-temperature cleanup, followed by liquid chromatography coupled to tandem mass spectrometry. Samples were extracted with acidified methanol/water (90:10), followed by low-temperature cleanup. Chromatographic separation was obtained using a cyano-bonded silica phase. The mobile phase was composed of water and acetonitrile, with both 0.1% formic acid and 2.5 mmol L^-1 ammonium formate. Electrospray ionization was used in both negative and positive modes. The single-laboratory validation approach enabled method performance assessment, and the necessary data to design a model for result expression were yielded. With this purpose, a systematic study of errors and uncertainties was performed. This new analytical approach aimed to minimize the use of highly expensive analytical standards, promoting economic viability to be applied by high-throughput routine laboratories. After its implementation on the Brazilian official monitoring program, positive results near the regulatory limits were obtained, demonstrating the fit for purpose of the method as a surveillance tool.

Evaluation of alternative environmentally friendly matrix solid phase dispersion solid supports for the simultaneous extraction of 15 pesticides of different chemical classes from drinking water treatment sludge

This study describes the development, optimization and validation of a method for the extraction of 15 pesticides of different chemical classes in drinking water treatment sludge (DWTS) by vortex-assisted Matrix Solid Phase Dispersion (MSPD) with determination by gas chromatography coupled to mass spectrometry. It focused on the application of alternative and different solid supports to the extraction step of the MSPD. The main parameters that influenced the extraction were studied in order to obtain better recovery responses. Recoveries ranged from 70 to 120% with RSD below 20% for all analytes. Limits of quantification (LOQ) of the method ranged from 5 to 500 μg kg^-1 whereas the analytical curves showed correlation coefficients above 0.997. The method under investigation used low volume of solvent (5 mL), low sample mass (1.5 g) and low mass of chitin (0.5 g), an environmentally friendly support. It has advantages, such as speed, simplicity and low cost material, over other methods. When the method was applied, 4 out of 15 pesticides were detected in the DWTS samples in concentrations below the LOQ.

Procedures of determining organic trace compounds in municipal sewage sludge-a review

Sewage sludge is the largest by-product generated during the wastewater treatment process. Since large amounts of sludge are being produced, different ways of disposal have been introduced. One tempting option is to use it as fertilizer in agricultural fields due to its high contents of inorganic nutrients. This, however, can be limited by the amount of trace contaminants in the sewage sludge, containing a variety of microbiological pollutants and pathogens but also inorganic and organic contaminants. The bioavailability and the effects of trace contaminants on the microorganisms of soil are still largely unknown as well as their mixture effects. Therefore, there is a need to analyze the sludge to test its suitability before further use. In this article, a variety of sampling, pretreatment, extraction, and analysis methods have been reviewed. Additionally, different organic trace compounds often found in the sewage sludge and their methods of analysis have been compiled. In addition to traditional Soxhlet extraction, the most common extraction methods of organic contaminants in sludge include ultrasonic extraction (USE), supercritical fluid extraction (SFE), microwave-assisted extraction (MAE), and pressurized liquid extraction (PLE) followed by instrumental analysis based on gas or liquid chromatography and mass spectrometry.

NiO and Co3O4 co-doped g-C3N4 nanocomposites with excellent photoelectrochemical properties under visible light for detection of tetrabromobisphenol-A

A NiO/Co₃O₄/g-C₃N₄ nanocomposite was prepared by one step thermal decomposition and it exhibited excellent photoelectrochemical activity for sensing TBBP-A.

Reductive dechlorination of tetrachlorobisphenol A by Pd/Fe bimetallic catalysts

The Pd/Fe bimetallic catalysts of micron sizes were synthesized and the rates of tetrachlorobisphenol A (TCBPA) degradation were measured under various conditions using a batch reactor system. The results showed that TCBPA was rapidly dechlorinated to tri-, di- and mono-chlorobisphenol A and to bisphenol A (BPA). The observed rate constants (k(obs)) were found to increase as functions of the Pd coverage on the Fe particles and the dosages of the catalysts within the reactors. The k(obs) value decreased as the initial TCBPA concentration increased, suggesting that the TCBPA dechlorination may follow a surface-site limiting Langmuir-Hinshelwood rate model. The weakly acidic solution, especially at or near pH 6.0, also favored the dechlorination of TCBPA. At pH 6.0, Pd coverage of 0.04 4 wt% and catalyst dosage of 5 g L(-1), TCBPA with an initial concentration of 20 μM was completely transformed within 60 min, and BPA was detected as the major product through the reaction time. Meanwhile, the k(obs) values measured at constant solution pH correlated linearly with the mass of particle-bound Pd introduced to the reactors, regardless of Pd/Fe catalyst dosage or Pd surface coverage. This study suggested that Pd/Fe catalysts could be potentially employed to rapidly degrade TCBPA in the contaminated environment.

Simultaneous determination of brominated phenols in soils

Brominated phenols (BPs), a widely used group of emerging flame retardants, are important environmental contaminants and exhibit endocrine disrupting potential. Method for simultaneous determination of tetrabromobisphenol A (TBBPA), tribromophenol (TBP), dibromophenols (DBPs) and monobromophenols (MBPs) in soils using gas chromatography-mass spectrometry analysis (GC/MS) was successfully developed. Cleanup methods for soil extracts including several solid-phase extraction cartridges and different elution solvents were compared and optimized. Florisil cartridge with dichloromethane as the elution reagent was selected for sample cleanup owing to its high and reproducible recoveries of the target analytes in soils. Derivatization conditions were tested and the optimal conditions were obtained with 20 microL silylation reagent at room temperature. The chromatographic separation was optimized with different columns and DB-XLB column was selected for its excellent separation of the analytes. The limits of detection for the target compounds were from 0.04 to 0.19 ng/g. Mean recoveries of the compounds from spiked soils exceeded 84% with a good reproducibility, excepting that the recovery of 2-bromophenol was relatively poor (lower than 55%) due to its instability. The developed method was applied to the determination of the BPs in the soils collected from e-waste sites. The contents of BPs in the soils were at ng/g levels with TBBPA and TBP the most frequently detected. To our knowledge, this is the first report for the simultaneous determination of TBBPA, TBP, DBPs and MBPs in soils.

Reductive debromination of tetrabromobisphenol A by Pd/Fe bimetallic catalysts

The bimetallic catalysts of micron sizes were synthesized and the rates of tetrabromobisphenol A (TBBPA) transformation were measured under various conditions using a batch reactor system. The results showed that TBBPA was rapidly debrominated to tri-, di- and mono-bromobisphenol A and to bisphenol A (BPA). The pseudo-first-order rate constants normalized to the specific surface area of the catalysts were found to increase as functions of the Pd coverage on the Fe particles and the dosages of the catalysts and the mass of Pd within the reactors. The rate constants were also decreasing as the solution pH increased. At pH 4.2, Pd coverage of 0.022wt% and catalyst dosage of 4gL(-1), 99% of TBBPA was transformed within 2min, and tri-, di-, and mono-bromobisphenol A were detected as the major intermediate products. After reaction for 45min, BPA was the only compound found in this specific system. Meanwhile, the rate constants measured at constant solution pH correlated linearly with the Pd mass introduced to the reactors, regardless of Pd/Fe catalyst dosage or Pd surface coverage. The study suggested that Pd/Fe catalysts could be used for efficiently treating brominated flame retardants extracted from e-wastes.

Occurrence and analysis of parabens in municipal sewage sludge from wastewater treatment plants in Madrid (Spain)

A rapid method for determination of seven parabens and two chlorinated by-products in sewage sludge was developed based on matrix solid-phase dispersion and gas chromatography-tandem mass spectrometry. The analytical procedure showed good recoveries that ranged from 80 to 125%, with relative standard deviations lower than 12% and low detection limits, ranging from 0.1 to 2.0 ng g(-1) dry weight. The developed method was applied to the analysis of sewage sludge collected during 2010 in 19 wastewater treatment plants (WWTPs) located in various urban, industrial or rural zones in Madrid (Spain). Methylparaben was found in most of the WWTPs sampled (95%) at levels between 5.1 and 26.2 ng g(-1) dry weight and propylparaben was detected in 74% of the WWTPs at levels up to 44.1 ng g(-1) dry weight. In order to study the temporal variation of parabens and two chlorinated parabens during a four-year period, sludge samples were collected from 3 selected WWTPs. The levels of methylparaben encountered were rather constant throughout the sampling period whereas propylparaben levels slightly increased. In one of the WWTPs monitored, isopropylparaben was found at the beginning of the sampling period but its content decreased and was not detected in the 2010 sampling.

Recent advances in enrichment techniques for trace analysis in capillary electrophoresis

CE is gaining great popularity as a well-established separation technique for many fields such as pharmaceutical research, clinical application, environmental monitoring, and food analysis, owing to its high resolving power, rapidity, and small amount of samples and reagents required. However, the sensitivity in CE analysis is still considered as being inferior to that in HPLC analysis. Diverse enrichment methods and techniques have been increasingly developed for overcoming this issue. In this review, we summarize the recent advances in enrichment techniques containing off-line preconcentration (sample preparation) and on-line concentration (sample stacking) to enhancing sensitivity in CE for trace analysis over the last 5 years. Some relatively new cleanup and preconcentration methods involving the use of dispersive liquid-liquid microextraction, supercritical fluid extraction, matrix solid-phase dispersion, etc., and the continued use and improvement of conventional SPE, have been comprehensively reviewed and proved effective preconcentration alternatives for liquid, semisolid, and solid samples. As for CE on-line stacking, we give an overview of field amplication, sweeping, pH regulation, and transient isotachophoresis, and the coupling of multiple modes. Moreover, some limitations and comparisons related to such methods/techniques are also discussed. Finally, the combined use of various enrichment techniques and some significant attempts are proposed to further promote analytical merits in CE.

Analysis of emerging organic contaminants in environmental solid samples

Spreading sewage sludge on agricultural lands has been actively promoted by national authorities as an economic way of recycling. However, as by-product of wastewater treatment, sewage sludge may contain toxic substances, which could be incorporated into agricultural products or be distributed in the environment. Moreover, sediments can be contaminated by the discharge of wastewater effluents into rivers. This article reviews the determination of emerging contaminants (surfactants, flame retardants, pharmaceuticals and personal care products) in environmental solid samples (sludge, soil and sediment). Sample preparation, including extraction and clean-up, as well as the subsequent instrumental determination of contaminants are discussed. Recent applications of extraction techniques, such as Soxhlet extraction, ultrasound assisted extraction, pressurised liquid extraction, microwave assisted extraction and matrix solid-phase dispersion to the analysis of emerging contaminants in environmental solid samples are reviewed. Determination of these contaminants, generally carried out by gas chromatography and liquid chromatography coupled with different detectors, especially mass spectrometry for the identification and quantification of residues, is also summarised and discussed.

Biodegradation of tetrachlorobisphenol-A in river sediment and the microbial community changes

This study investigated the aerobic degradation of tetrachlorobisphenol-A (TCBPA) in sediment samples collected at three sites along Erren River in southern Taiwan. TCBPA biodegradation rate constants (k(1)) and half-lives (t(1/2)) ranged from 0.03 to 0.06 day(-1) and 11.6 to 23.1 days, respectively. The biodegradation of TCBPA was enhanced by the addition of cellulose, yeast extract, sodium chloride, brij 30, brij 35, surfactin, and rhamnolipid. Of the micro-organism strains isolated from the sediment, we found that strains L1 and L5 (identified as Bacillus megaterium and Pseudomonas putida) expressed the best biodegrading ability. The inoculation of sediment with the TCBPA-degrading bacteria could enhance the efficiency of degradation.

An experimental design approach employing artificial neural networks for the determination of potential endocrine disruptors in food using matrix solid-phase dispersion

Matrix solid-phase dispersion (MSPD) as a sample preparation method for the determination of two potential endocrine disruptors, linuron and diuron and their common metabolites, 1-(3,4-dichlorophenyl)-3-methylurea (DCPMU), 1-(3,4-dichlorophenyl) urea (DCPU) and 3,4-dichloroaniline (3,4-DCA) in food commodities has been developed. The influence of the main factors on the extraction process yield was thoroughly evaluated. For that purpose, a 3 fractional factorial design in further combination with artificial neural networks (ANNs) was employed. The optimal networks found were afterwards used to identify the optimum region corresponding to the highest average recovery displaying at the same time the lowest standard deviation for all analytes. Under final optimal conditions, potato samples (0.5 g) were mixed and dispersed on the same amount of Florisil. The blend was transferred on a polypropylene cartridge and analytes were eluted using 10 ml of methanol. The extract was concentrated to 50 microl of acetonitrile/water (50:50) and injected in a high performance liquid chromatography coupled to UV-diode array detector system (HPLC/UV-DAD). Recoveries ranging from 55 to 96% and quantification limits between 5.3 and 15.2 ng/g were achieved. The method was also applied to other selected food commodities such as apple, carrot, cereals/wheat flour and orange juice demonstrating very good overall performance.

Application of matrix solid-phase dispersion to the determination of amitrole and urazole residues in apples by capillary electrophoresis with electrochemical detection

A new method based on matrix solid-phase dispersion (MSPD) extraction was studied for the extraction of amitrole (3-amino-1,2,4-triazole), and its metabolite urazole (3,5-dihydroxy-1,2,4-triazole), in apple samples. The influence of experimental conditions on the yield of the extraction process and on the efficiency of the cleanup step was evaluated. Determination was carried out by capillary electrophoresis (CE) with electrochemical detection, demonstrating the compatibility between MSPD and CE techniques. The method has been successfully applied to different apple varieties. Recoveries in samples spiked at 1.6 and 1.7 microg g(-1) for amitrole and urazole were 88 and 82%, respectively. The limits of detection were 0.4 microg g(-1) for both compounds using electrochemical detection.

Molecularly imprinted-matrix solid-phase dispersion for selective extraction of five fluoroquinolones in eggs and tissue

A novel highly selective sample cleanup procedure combining molecular imprinting and matrix solid-phase dispersion (MI-MSPD) was developed for the simultaneous isolation of ofloxacin, pefloxacin, norflorxacin, ciprofloxacin, and enrofloxacin in chicken eggs and swine tissues followed by high-performance liquid chromatography with fluorescence detection. The novel ofloxacin imprinted polymers synthesized in water-containing systems show high selectivity for the five fluoroquinolones in aqueous environment and the affinity can be easily adjusted by the pH of solution. Compared with conventional MSPD methods, using MIPs as selective MSPD sorbents, the five fluoroquinolones could be selectively extracted from a biological matrix and all matrix interferences were eliminated simultaneously. The average recoveries of the five fluoroquinolones were ranged from 85.7 to 104.6% for eggs and 86.8 to 102.7% for tissues with relative standard deviations of less than 7.0%. Detection limits for the identification of the five fluoroquinolones in eggs and tissues ranged from 0.05 to 0.09 ng/g.

Optimization of the matrix solid-phase dispersion sample preparation procedure for analysis of polycyclic aromatic hydrocarbons in soils: comparison with microwave-assisted extraction

A fast and simple preparation procedure based on the matrix solid-phase dispersion (MSPD) technique is proposed for the first time for the isolation of 16 polycyclic aromatic hydrocarbons (PAHs) from soil samples. Naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[e]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene, benzo[g,h,i]perylene, and indeno[1,2,3-c,d]pyrene were considered in the study. Extraction and clean-up of samples were carried out in a single step. The main parameters that affect extraction yield, such as dispersant, type and amount of additives, clean-up co-sorbent and extractive solvent were evaluated and optimized. The addition of an alkali solution in MSPD was required to provide quantitative recoveries. Analytical determinations were carried out by high performance liquid chromatography (HPLC) with fluorescence detection. Quantification limits (between 0.01 and 0.6 ng g(-1) dry mass) were well below the regulatory limits for all the compounds considered. The extraction yields for the different compounds obtained by MSPD were compared with the yields obtained by microwave-assisted extraction (MAE). To test the accuracy of the MSPD technique, the optimized methodology was applied to the analysis of standard reference material BCR-524 (contaminated industrial soil), with excellent results.

Optimisation of a matrix solid-phase dispersion method for the determination of organophosphate compounds in dust samples

A fast and inexpensive sample preparation procedure based on the matrix solid-phase dispersion (MSPD) technique is proposed for the isolation of several organophosphate esters (mainly employed as flame retardants and plasticizers) from indoor dust samples. Extraction and clean-up were carried out in a single step and target compounds were determined by gas chromatography (GC) with nitrogen-phosphorus detection (NPD). The main parameters affecting extraction yield and selectivity, such as type and amount of dispersant material, clean-up co-sorbent and extraction solvent, were evaluated and optimised. Under final conditions, 0.5 g of dust were dispersed with equal amounts of anhydrous sodium sulphate and Florisil, and loaded on the top of a polypropylene cartridge containing 0.5 g of alumina. The dispersed sample was washed with 2 mL of n-hexane to remove the least polar interferences and analytes were eluted with 3 mL of acetone. Recoveries of the proposed method for spiked samples ranged from 80 to 116%, and the day-to-day variability remained between 5 and 10%. Data on levels of organophosphate species in dust from private houses and vehicle cabins are provided. In both cases, the lowest concentrations corresponded to the short chain, non-chlorinated, alkyl organophosphates, whereas mean values above 1 microg g(-1) were measured for the rest of analytes.

Determination of Parabens and Triclosan in Indoor Dust Using Matrix Solid-Phase Dispersion and Gas Chromatography with Tandem Mass Spectrometry

A simple sample preparation method for the determination of four parabens and triclosan in indoor dust is presented. Analytes were extracted from the sample and isolated from interfering species using the matrix solid-phase dispersion technique. After that, they were silylated and determined by gas chromatography combined to tandem mass spectrometry (GC/MS/MS). The influence of several factors on the yield and selectivity of the extraction was evaluated in detail. Under final working conditions, samples (0.5 g) were mixed with the same amount of anhydrous sodium sulfate and dispersed on 1.25 g of C18. This blend was transferred to the top of a polypropylene cartridge containing 2 g of Florisil. After removing less polar species with 10 mL of dichloromethane, analytes were recovered using 10 mL of acetonitrile. This extract was concentrated to 1 mL, derivatized, and injected in the GC/MS/MS system. Derivatization was carried out at 45 degrees C in 5 min using 100 microL of N-methyl-N-(tert-butyldimethylsilyl) trifluoroacetamide. Quantification limits from 0.6 to 2.6 ng/g and absolute recoveries between 80 and 114% were achieved. Analysis of dust samples demonstrated the presence of the target species in indoor dust from private houses. The highest average concentration (702 ng/g) corresponded to triclosan.