Aqueous Environmental Matrices Research Articles

Evaluating bottle liquid-liquid extraction technique for monitoring residual levels of organochlorine pesticides in wastewater treatment-associated matrices

The gold standard for recovering residual organochlorine pesticides from wastewater and aqueous environmental matrices is the continuous liquid-liquid extraction (CLLE) technique that requires methylene chloride (CH2Cl2) as solvent at its refluxing temperature. In light of a recent USEPA proposed prohibitions and workplace protections for CH2Cl2 (due to its toxicity) and the fact that CLLE requires expensive and hard-to-acquire glassware, an alternative to CLLE as currently practiced is needed. The bottle liquid-liquid extraction (BLLE) technique, demonstrated for extracting semi-volatile organic contaminants from surface water, is potentially a low cost and high throughput alternative for such recovery. BLLE is cheaper and has a smaller laboratory footprint. The technique, performed at ambient temperature in a tightly capped bottle, requires less amount of solvent and contains solvent vapor within the bottle. The latter means less CH2Cl2 is encountered in the workplace. In this study, BLLE was performed directly in 1-L amber sampling bottles and shown to recover 21 organochlorine pesticides as efficiently as CLLE from influents and effluents of two wastewater treatment plants Because no statistical differences were found between CLLE (mean = 77.4, SD = 9.28) and BLLE (mean = 79.1, SD = 14.3); t(22) = 0.548, p(same mean) = 0.58, even though CLLE recovered more pesticides than BLLE by 5.18 ± 8.15%, these techniques are amenable to interchangeable usage. The systematic bias so far detected fits the expression BLLE = 1.4[CLLE] – 35 (r = 0.88). Both CLLE and BLLE recoveries were consistently higher for 4,4′-DDD and lower for aldrin, heptachlor and endrin aldehyde. Diethyl ether addition, as some suggested, did not improve BLLE.Synopsis: There is need to find a cheap, reliable and high throughput technique for purifying SVOCs from aqueous environmental media efficiently. BLLE, a little known technique, fulfils this need.

Synthesis, characterization, and application of Cu-substituted LaNiO3 perovskites as photocatalysts and/or catalysts for persulfate activation towards pollutant removal

The presence of emerging contaminants in environmental aqueous matrices is an ever-growing problem, since conventional wastewater treatment methods fail to adequately remove them. Therefore, the application of non-conventional methodologies such as advanced oxidation processes is of great importance to tackle this modern problem. Photocatalysis as well as catalytic activation of persulfates are promising techniques in this field as they are capable of eliminating various emerging contaminants, and current research aims to develop new materials that can be utilized for both processes. In this light, the present study focused on the use of a simple sol-gel-combustion methodology to synthesize Cu-substituted LaNiO3 perovskite materials in an attempt to improve the photocatalytic and catalytic performance of pure LaNiO3, using molar ratios of Cu:Ni that have not been previously reported in the literature. The morphological, structural, and optical features of the synthesized materials were characterized by a series of analytical techniques (e.g., X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, diffuse reflectance spectroscopy, etc.). Also, their performance as photocatalysts, persulfate anion activators and simultaneously as photocatalysts/persulfate anion activators (hybrid) was evaluated by conducting laboratory-scale experiments using phenol (phenolics) as a model emerging contaminant. Interestingly, the results revealed that LaCu0.25Ni0.75O3 exhibited the best efficiency in all the applied processes, which was mainly attributed to the introduction of oxygen vacancies in the structure of the substituted material. The contribution of selected reactive species in the hybrid photocatalytic/catalytic experiments utilizing LaCu0.25Ni0.75O3 as a (photo)catalyst was investigated using appropriate scavengers, and the results suggested that singlet oxygen is the most dominant. Additionally, the stability of all synthesized perovskites was assessed by monitoring the concentration of the leached Cu and/or Ni cations at the end of every applied process. Finally, the reusability of LaCu0.25Ni0.75O3 was evaluated in three consecutive catalytic cycles using the hybrid experiment methodology, as this process demonstrated the best efficiency in terms of phenolics removal, and the results were rather promising.

Cyclodextrin-silica hybrid materials: synthesis, characterization, and application in pesticide aqueous removal.

Overusing and misusing pesticides, including paraquat (PQ), have led to numerous environmental contamination complications. PQ is an emerging bio-accumulative contaminant that is present in environmental aqueous matrices. Adsorption techniques are part of a set of technologies applied in ecological remediation, known for their high effectiveness in removing aqueous PQ. A study of the PQ adsorption capacity of three cyclodextrin-silica nanocomposites (α-CDSi, β-CDSi, and γ-CDSi) from contaminated waters is presented in this paper. The cyclodextrin-silica nanocomposites were synthesized via an esterification reaction between the inorganic matrix and cyclodextrins (CDs) (α, β, and γ) and were characterized physicochemically by spectroscopic, thermal, and surface methods. Their PQ removal performance from contaminated aqueous media was studied under different experimental conditions. The results showed a fast adsorptive response in removal treatment studies over time. Adsorption capacities of 87.22, 57.17, and 77.27mg.g-1 were found for α-CDSi, β-CDSi, and γ-CDSi, respectively, at only 30min of treatment. Thermodynamic studies indicated spontaneous and exothermic adsorption processes. The removal assays responded mainly to physisorption mechanisms with contributions from chemisorption mechanisms. Spectroscopic assays showed a strong interaction of PQ with the adsorbents used. Innovative CDSi nanocomposites have proven to be highly efficient in applying aqueous PQ remediation, thus proving to be sustainable adsorbents of contaminants of emerging importance worldwide.

Isolation and characterization of Rhodococcus sp. GG1 for metabolic degradation of chloroxylenol

The coronavirus disease 2019 (COVID-19) pandemic has significantly increased the demand of disinfectant use. Chloroxylenol (para-chloro-meta-xylenol, PCMX) as the major antimicrobial ingredient of disinfectant has been widely detected in water environments, with identified toxicity and potential risk. The assessment of PCMX in domestic wastewater of Macau Special Administrative Region (SAR) showed a positive correlation between PCMX concentration and population density. An indigenous PCMX degrader, identified as Rhodococcus sp. GG1, was isolated and found capable of completely degrading PCMX (50 mg L−1) within 36 h. The growth kinetics followed Haldane's inhibition model, with maximum specific growth rate, half-saturation constant, and inhibition constant of 0.38 h−1, 7.64 mg L−1, and 68.08 mg L−1, respectively. The degradation performance was enhanced by optimizing culture conditions, while the presence of additional carbon source stimulated strain GG1 to alleviate inhibition from high concentrations of PCMX. In addition, strain GG1 showed good environmental adaptability, degrading PCMX efficiently in different environmental aqueous matrices. A potential degradation pathway was identified, with 2,6-dimethylhydroquinone as a major intermediate metabolite. Cytochrome P450 (CYP450) was found to play a key role in dechlorinating PCMX via hydroxylation and also catalyzed the hydroxylated dechlorination of other halo-phenolic contaminants through co-metabolism. This study characterizes an aerobic bacterial pure culture capable of degrading PCMX metabolically, which could be promising in effective bioremediation of PCMX-contaminated sites and in treatment of PCMX-containing waste streams.

Human exposure to persistent and mobile chemicals: A review of sources, internal levels and health implications

Persistent and mobile chemicals (PMs) are highly polar organic chemicals of anthropogenic origin, which have been documented as an emerging issue of concern for environmental and human health and for which policy needs have recently been identified. Since PMs are recognized as a serious threat to water resources and drinking water, many studies have focused on the occurrence and fate of PMs in aqueous environmental matrices, especially surface water, groundwater and drinking water but considerably less so directly on human exposure. Consequently, our understanding of human exposure to PMs is still limited. In this context, the main objectives of this review are to provide reliable information on PMs and comprehensive knowledge about human internal and relevant external exposure to PMs. This review highlights the occurrence of eight selected PMs: melamine and its derivatives and transformation products, quaternary ammonium compounds, benzotriazoles, benzothiazole and their derivatives and transformation products, 1,4-dioxane, 1,3-di-o-tolylguanidine, 1,3-diphenylguanidine and trifluoromethane sulfonic acid in human matrices (blood, urine, etc.) and environmental samples relevant to human exposure (drinking water, food, indoor dust, etc.). In addition, human biomonitoring data is discussed in the framework of the chemicals risk management policy. Current knowledge gaps of selected PMs from a human exposure perspective, as well as future research needs were also identified. While PMs discussed in this review have been found in various environmental matrices relevant for human exposure, it is important to note that human biomonitoring data for some PMs is very limited. Available data on the estimated daily intakes of some PMs suggest that they do not pose an immediate concern for human exposure.

Broad-range extraction of highly polar to non-polar organic contaminants for inclusive target analysis and suspect screening of environmental samples

The lack of carefully optimized extraction techniques for the analysis of compounds with diverse polarities limits the identification of toxic pollutants in aqueous environmental matrices, particularly those that are considered persistent and mobile organic compounds (PMOCs). Tailored extraction techniques for specific classes of chemicals often result in very low to no extraction of either very polar or relatively non-polar chemicals, depending on the sorbent used. Hence, it is crucial to develop a balanced extraction for a wider range of polarity, especially for non-target analysis of chemical residues, in order to capture the occurrence of the full profile of micropollutants. Herein, a tandem solid-phase extraction (SPE) technique incorporating both hydrophilic-lipophilic balance (HLB) and mixed-mode cation exchange (MCX) sorbents was developed to extract and analyze 60 model compounds with a wide range of polarities (log Kow from ‐1.9 to 5.5) from untreated sewage matrices. Extraction efficiencies were assessed in NanoPure™ water and untreated sewage samples; 51 compounds in NanoPure™ water and 44 compounds in untreated sewage had ≥60 % extraction recoveries using the developed tandem SPE method. The method limits of detection ranged from 0.25 to 88 ng/L in untreated sewage matrix. The applicability of the extraction method was demonstrated in untreated wastewater samples; using the tandem SPE for suspect screening analysis captured an additional 22 compounds that were not extracted when using the HLB sorbent only. The optimized SPE method was also evaluated for the extraction of per- and polyfluoroalkyl substances (PFAS) by analyzing the same sample extracts under negative electrospray ionization liquid chromatography-tandem mass spectrometry (LC-MS/MS). The wastewater samples revealed the presence of sulfonamide-, sulfonic-, carboxylic-, and fluorotelomer sulfonic- PFAS with chain lengths 8, 4–8, 4–9, and 8, respectively, indicating that the tandem SPE procedure provides an efficient one-step extraction for the analysis of PMOCs that include pharmaceuticals, pesticides, and PFAS.

Development of biomimetic hexapeptide functionalized monolithic material for capillary microextraction of microcystins in environmental waters

In this work, a histidine-tagged hexapeptide functionalized monolithic material is described for the efficient capillary microextraction (CME) of microcystins (MCs) from environment waters. 1-Vinylimidazole (VIM) monomer was utilized to synthesize the matrix polymer monolith by the copolymerization with divinylbenzene (DVB) crosslinker in the presence of radical initiator azobisisobutyronitrile (AIBN). The affinity sorbent was then prepared by a metal ion chelation-based multi-step approach, in which the histidine tag peptide Trp-His-Trp-Leu-Gln-Trp (WHWLQW) was functionalized on a Cu2+ modified polymer monolith via a chelation reaction between the imidazole group of histidine and Cu2+. The resultant WHWLQW functionalized monolithic material had high affinity, hierarchical porosity and good mechanical stability. Especially, it exhibited favorable enrichment capacity for MCs compared to other affinity materials as previously reported. With the optimized CME protocol, MCs at ultra-trace level can be analyzed by CME coupled to high performance liquid chromatography-mass spectrometry (HPLC-MS) in different aqueous environmental matrices. The average recoveries were ranged from 89.3% to 104.5% with relative standard deviations (RSD%) of 2.1–8.4, demonstrating high extraction efficiency and repeatability. The limits of detection (LODs) of MCs were determined to be 0.28–0.45 ng L-1. This novel biomimetic sorbent shows promising potential for the enrichment of ultra-trace pollutants in environment waters.

Feasibility of a Heterogeneous Nanoscale Zero-Valent Iron Fenton-like Process for the Removal of Glyphosate from Water

Glyphosate is a widely used herbicide, and it is an important environmental pollutant that can have adverse effects on human health. Therefore, remediation and reclamation of contaminated streams and aqueous environments polluted by glyphosate is currently a worldwide priority. Here, we show that the heterogeneous nZVI-Fenton process (nZVI + H2O2; nZVI: nanoscale zero-valent iron) can achieve the effective removal of glyphosate under different operational conditions. Removal of glyphosate can also take place in the presence of excess nZVI, without H2O2, but the high amount of nZVI needed to remove glyphosate from water matrices on its own would make the process very costly. Glyphosate removal via nZVI--Fenton was investigated in the pH range of 3-6, with different H2O2 concentrations and nZVI loadings. We observed significant removal of glyphosate at pH values of 3 and 4; however, due to a loss in efficiency of Fenton systems with increasing pH values, glyphosate removal was no longer effective at pH values of 5 or 6. Glyphosate removal also occurred at pH values of 3 and 4 in tap water, despite the occurrence of several potentially interfering inorganic ions. Relatively low reagent costs, a limited increase in water conductivity (mostly due to pH adjustments before and after treatment), and low iron leaching make nZVI-Fenton treatment at pH 4 a promising technique for eliminating glyphosate from environmental aqueous matrices.

Electrografting a p‐Propylaniline/L–Cys Nanofilm onto a Glassy Carbon Electrode Resulting in Enhanced Electrosensing of Cd(II), Pb(II) and Hg(II)

AbstractA glassy carbon electrode (GCE) was chemically modified with p‐propylaniline/L–Cys molecules for the sensitivity determination of Cd(II), Pb(II) and Hg(II) in aqueous medium. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) characterized passivation of the electrode and 97.4 % surface coverage with p‐propylaniline/L–Cys molecules. Nanofilm coating was characterized by cyclic voltammetry (CV), atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR) techniques to observe the surface morphology. The porous structure uniformly distributed thiol, amine and carboxylate groups throughout the coating to selectively coordinate and preconcentrate the three metal ions. Under the optimized conditions (deposition potential: −1 V vs. SCE, deposition time: 90s), square wave anodic stripping voltammetry (SWASV) electroanalysis results indicated the linear increment of electrochemical signals with an increase in the concentration of Cd(II), Pb(II) and Hg(II) in range of 2.5 to 30 μg L−1. Based on the calibration plot, limit of detection (LOD, 3σ/m) are 0.103 μg L−1, 0.055 μg L−1 and 0.01 μg L−1 respectively. Analysis of drinking and tap water samples demonstrated precision and accuracy of the electrode as a prospective sensor for analysis of more complex aqueous environmental matrices.

A multi-residue chiral liquid chromatography coupled with tandem mass spectrometry method for analysis of antifungal agents and their metabolites in aqueous environmental matrices.

The presence and fate of antifungal agents in the environment have hardly been investigated. This is despite the increased usage of antifungal agents and higher prevalence of antifungal resistance. Stereochemistry of antifungal agents has been largely overlooked due to lack of analytical methods enabling studies at the enantiomeric level. This paper introduces a new analytical method for combined separation of achiral and chiral antifungal agents and their metabolites with the utilization of chiral chromatography coupled with triple quadrupole tandem mass spectrometry to enable comprehensive profiling of wide-ranging antifungal agents and their metabolites in environmental matrices. The method showed very good linearity and range (r2 > 0.997), method accuracy (61-143%) and precision (3-31%) as well as low (ng L-1) MQLs for most analytes. The method was applied in selected environmental samples. The following analytes were quantified: fluconazole, terbinafine, N-desmethyl-carboxyterbinafine, tebuconazole, epoxiconazole, propiconazole and N-deacetyl ketoconazole. They were predominantly present in the aqueous environment (as opposed to wastewater) with sources linked with animal and plant protection rather than usage in humans. Interestingly, chiral fungicides quantified in river water were enriched with one enantiomer. This might have consequences in terms of their ecological effects which warrants further study.

Insights into total estrogenic activity in a sewage-impacted urban stream assessed via ER transcriptional activation assay: Distribution between particulate and dissolved phases

Endocrine disrupting chemicals (EDC) are exogenous substances that can potentially mimic hormonal substances and cause adverse effects on the endocrine system of living beings. The behavior and fate of these compounds in the environment is directly related to their physical-chemical properties, which indicate great affinity for solid and organic particles and suggest an inherent mechanism of fractionation between dissolved and particulate phases of aqueous matrices. However, few studies have been considering this fact when quantifying these pollutants and their effects through bioassays. In this study, the fractionation of estrogenic substances between dissolved and particulate phases in an urban stream was investigated via estrogenic activity evaluation by the YES assay. Two fractions of suspended solids (< 0.7 µm and between 0.45 and 0.7 µm) and the dissolved phase were considered and two approaches of SPE percolations were applied. Total estradiol equivalent (E2-Eq) values were observed in the 29–65 ng L−1 range, of which 35–62% were associated with the particulate phase. Most of the estrogenicity was associated with particles between 0.45 and 0.7 µm, whereas cytotoxicity was induced by extracts of particles greater than 0.7 µm. Results demonstrated the importance of solid fractions analysis towards the quantification of total estrogenic activity from aqueous environmental matrices and highlights the relevance of controlling fine suspended solids in sewage treatment plant effluents, regarding the control of endocrine disrupters in the environment.

Microbial electrochemical biosensor for rapid detection of naphthenic acid in aqueous solution

Abstract In processed water generated from oil sands operations, naphthenic acids (NAs) are identified as one of the primary sources of acute toxicity and were assessed for their endocrine-disrupting potentials. Hence, the monitoring of NAs in aqueous environmental matrices is crucial for oil sands and crude oil production industries. Commonly used analytical methods for NAs include Fourier transform infrared spectroscopy, gas chromatography–mass spectrometry, and high-performance liquid chromatography. However, these methods are time-consuming, expensive, and samples must be sent to an analytical lab for analysis. In this study, we first demonstrated microbial electrochemical cell (MXC)-based biosensor for the rapid detection of a model NA compound (cyclohexane carboxylic acid) in water samples. Under the continuous closed-circuit operation of MXC biosensor, electrical responses (peak currents) were fairly proportional (R2 = 0.64) to the model NA concentrations ranging from 50 to 250 mg COD/L. However, the charging-discharging operation of biosensor significantly increased the peak currents by 90–124 folds higher than that observed for continuous closed-circuit operation. Besides, a linear relationship between model NA concentrations and the peak currents (R2 = 0.96) was observed. Furthermore, it has been revealed that the biosensor would be sensitive to salinity levels and temperature changes; however, once calibrated it can be used for measurement of model NA concentrations. Overall, the results of this study demonstrated that with further development, MXC biosensor could be used as a simple bioanalytical tool for monitoring NA concentrations in oil sands process-affected water.

Polyelectrolyte Based Sensors as Key to Achieve Quantitative Electronic Tongues: Detection of Triclosan on Aqueous Environmental Matrices.

Triclosan (TCS) is a bacteriostatic used in household items that promotes antimicrobial resistance and endocrine disruption effects both to humans and biota, raising health concerns. In this sense, new devices for its continuous monitoring in complex matrices are needed. In this work, sensors, based on polyelectrolyte layer-by-layer (LbL) films prepared onto gold interdigitated electrodes (IDE), were studied. An electronic tongue array, composed of (polyethyleneimine (PEI)/polysodium 4-styrenesulfonate (PSS))5 and (poly(allylamine hydrochloride/graphene oxide)5 LbL films together with gold IDE without coating were used to detect TCS concentrations (10−15–10−5 M). Electrical impedance spectroscopy was used as means of transduction and the obtained data was analyzed by principal component analysis (PCA). The electronic tongue was tested in deionized water, mineral water and wastewater matrices showing its ability to (1) distinguish between TCS doped and non-doped solutions and (2) sort out the TCS range of concentrations. Regarding film stability, strong polyelectrolytes, as (PEI/PSS)n, presented more firmness and no significant desorption when immersed in wastewater. Finally, the PCA data of gold IDE and (PEI/PSS)5 sensors, for the mineral water and wastewater matrices, respectively, showed the ability to distinguish both matrices. A sensitivity value of 0.19 ± 0.02 per decade to TCS concentration and a resolution of 0.13 pM were found through the PCA second principal component.

Overview of electronic tongue sensing in environmental aqueous matrices: potential for monitoring emerging organic contaminants

Emerging organic contaminants (EOC) are synthetic or naturally occurring chemicals that have the potential to enter the environment and cause known or suspected adverse ecological and human health effects. Despite not being commonly monitored, EOC are often detected in effluents and water bodies because of their inefficient removal in conventional wastewater treatment plants. There is a growing concern about the presence and impact of EOC as well as the need for reliable and effective water monitoring using sensors capable of detecting the target molecules in complex media. Due to their specificities, such as fast response times, low cost, portability and user-friendly operation, electronic tongue (e-tongue) systems present some advantages over the traditional analytical techniques (e.g., chromatographic systems) used for environmental monitoring. We reviewed e-tongue sensors, focusing on their ability for real-time environmental monitoring. A bibliometric evaluation was carried out, along with a study of the status of the existing e-tongue systems, how they worked, and their applications in different fields. The potential of e-tongue sensors to detect organic contaminants in aqueous environmental matrices is discussed, with a particular focus on EOC.

Solar photo-Fenton oxidation for the removal of ampicillin, total cultivable and resistant E. coli and ecotoxicity from secondary-treated wastewater effluents

Urban, hospital and pharmaceutical industry wastewater effluents are among the main sources of antibiotics’ and other antimicrobial agents’ contamination in soil and water ecosystems, especially in countries where wastewater reuse is applied. Ampicillin (AMP), which is the first semi-synthetic broad spectrum penicillin that was released on the market in 1961 has been detected in treated wastewater effluents worldwide, at concentrations ranging from sub-ng/L up to 27 μg/L, as well as in various environmental aqueous matrices up to 13.7 μg/L, highlighting its recalcitrance to conventional biological treatment. Nevertheless, the degradation potential of AMP via advanced chemical oxidation processes, which are widely considered as promising alternatives of conventional technologies, hardly has been investigated. Thus, this study aims at assessing the efficiency of solar photo-Fenton process at degrading AMP from secondary-treated wastewater effluents under various experimental conditions. The degradation rate of AMP via solar photo-Fenton oxidation fitted well the pseudo-first-order kinetic model. AMP was completely degraded after 30 min of treatment at various H2O2 doses (25–100 mg/L) under acidic pH, while its degradation was pronounced at mild alkaline conditions (inherent pH) (100% removal after 5 min). Total cultivable and AMP-resistant E. coli was completely inactivated after 180 min of treatment at the optimum operational conditions, and no regrowth was observed. Finally, the ecotoxicity results showed that the process was capable of eliminating the toxicity towards Daphnia magna after 180 min, providing thus a more complete evaluation of the overall efficiency of the process.

Automated bundled hollow fiber array-liquid-phase microextraction with liquid chromatography tandem mass spectrometric analysis of perfluorinated compounds in aqueous media

An automated bundled hollow fiber array (BHF)-liquid-phase microextraction (LPME) methodology in combination with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) has been developed for the determination of perfluorinated compounds (PFCs) in environmental aqueous matrices. Eight PFCs were considered, including perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorotetradecanoic acid. Experimental parameters influencing extraction efficiency, such as number of hollow fibers in the BHF extraction device, type of extraction and desorption solvent, extraction conditions (stirring rate, temperature and duration), elution conditions and the salting out effect were examined. Under the most favourable conditions, enrichment factors of between 9 and 40 were achieved for the target compounds when extracting from 10 mL of sample. Good intra and inter-day precision were obtained with relative standard deviations of less than 12%. The linearity range investigated was between 5 and 10,000 ng L−1, with coefficients of determination (r2) ≥ 0.991. The developed method was applied for the UHPLC-MS/MS determination of environmental PFCs in industrial water discharge samples. The automation of BHF-LPME together with UHPLC-MS/MS rendered the method efficient, rapid and sensitive to determine PFCs, with the possibility of on-site real-time monitoring of contaminants in environmental waters.

Simultaneous enantioselective determination of six pesticides in aqueous environmental samples by chiral liquid chromatography with tandem mass spectrometry.

A robust and sensitive method was developed for the enantiomeric analysis of six chiral pesticides (including metalaxyl, epoxiconazole, myclobutanil, hexaconazole, napropamide, and isocarbophos) in aquatic environmental samples. The optimized chromatographic conditions for the quantification of all the 12 enantiomers were performed with Chiralcel OD-RH column using mobile phase consisting of 0.1% aqueous formic acid and acetonitrile operated under reversed-phase conditions and then analyzed using liquid chromatography with tandem mass spectrometry. Twelve enantiomers were detected in multiple reaction monitoring mode. Solid-phase extraction and dispersive liquid-liquid microextraction were employed in this study. Response surface methodology was applied to assist in the dispersive liquid-liquid microextraction optimization. Under the optimum conditions, recoveries of pesticides enantiomers varied from 83.0 to 103.2% at two spiked levels with relative standard deviation less than 11.5%. The concentration factors were up to 1000 times. Method detection and quantification limits varied from 0.11 to 0.48ng/L and from 0.46 to 1.49ng/L, respectively. Finally, this method was used to determination of the enantiomers composition of the six pesticides in environmental aqueous matrices, which will help better understand the behavior of individual enantiomer and make accurate risk assessment to ecosystems.

Utilization of large volume zwitterionic hydrophilic interaction liquid chromatography for the analysis of polar pharmaceuticals in aqueous environmental samples: Benefits and limitations

Benefits and limitations of HILIC were studied for the analysis of extreme polar organic contaminants in aqueous environmental matrices. A sensitive analytical method was developed and validated for the detection of 11 pharmaceuticals, 15 pharmaceutical metabolites and transformation products and the artificial sweetener acesulfame in aqueous environmental samples. The analytical method consisted of a simple and non-specific sample preparation based on freeze-drying followed by detection with large injection volume (70 μL) zwitterionic HILIC-ESI-MS/MS. Robustness studies showed a high sensitivity of the retention times and peak shapes to variations of the acetonitrile/water ratio of both the eluent and the diluent. Thus, a thorough sample and eluent preparation is required to obtain reproducible results. Extreme matrix effects of >200% were observed for emtricitabine and acyclovir, which could be traced to the co-elution of nitrate and chloride, respectively. These matrix effects and those of other analytes could be efficiently compensated by using deuterated, 13C and 15N-labeled internal standards. The developed method was able to detect the selected 27 analytes in treated wastewater, surface water and groundwater down to limit of quantification (LOQ) in the lower ng/L range. Appreciable concentrations were detected, ranging up to 110 μg/L (guanyl urea) in treated wastewater, up to 5.1 μg/L (oxipurinol) in surface water and up to 6.1 μg/L (acesulfame) in groundwater. In a German drinking water, only the X-ray contrast medium diatrizoate and the artificial sweetener acesulfame were quantified above LOQ with 0.19 μg/L and 0.35 μg/L, respectively.

Electrochemical Degradation of Lincomycin in Prepared and Environmental Aqueous Matrices

Electrochemical Degradation of Lincomycin in Prepared and Environmental Aqueous Matrices

A static headspace GC‐MS/MS method for the determination of ethanol, iso‐butanol, and n‐butanol at nanomolar concentrations in aqueous environmental samples

AbstractThe increased use of small molecular weight alcohols such as ethanol and potentially butanol isomers as biofuels has raised questions about the fate of these compounds in the environment once emitted. In order to address these questions, a method for the simultaneous determination of nanomolar concentrations of ethanol, n‐butanol, and iso‐butanol in aqueous environmental matrices is presented. The method consists of static headspace gas chromatograph‐mass spectrometer/mass spectrometer (GC‐MS/MS) analysis with detection limits of 28 nM for ethanol and 9 nM for each butanol isomer. Accuracy of the new method was verified by comparing ethanol concentrations in authentic environmental samples by an independent technique utilizing solid phase microextraction (SPME). Results of an intercomparison study between the static headspace GC‐MS/MS and SPME analyses produced a trend line with a slope of unity demonstrating that the methods produced statistically equivalent ethanol concentrations. Spiked additions of each alcohol in a variety of aqueous environmental matrices gave recoveries greater than 90% validating the accuracy of the headspace GC‐MS/MS analysis. The new static headspace GC‐MS/MS analysis represents the first methodology available with demonstrated accuracy in an array of environmental matrices with the requisite limit of detection capable of quantifying several alcohols in one analysis with minimal sample preparation and sample size requirement.