Using chiral liquid chromatography quadrupole time-of-flight mass spectrometry for the analysis of pharmaceuticals and illicit drugs in surface and wastewater at the enantiomeric level

Rejection of trace organic compounds by membrane processes: mechanisms, challenges, and opportunities

This work critically reviews the application of various membrane separation processes (MSPs) in treating water polluted with trace organic compounds (TOrCs) paying attention to nanofiltration (NF), reverse osmosis (RO), membrane bioreactor (MBR), forward osmosis (FO), and membrane distillation (MD). Furthermore, the focus is on loopholes that exist when investigating mechanisms through which membranes reject/retain TOrCs, with the emphasis on the characteristics of the model TOrCs which would facilitate the identification of all the potential mechanisms of rejection. An explanation is also given as to why it is important to investigate rejection using real water samples, especially when aiming for industrial application of membranes with novel materials. MSPs such as NF and RO are prone to fouling which often leads to lower permeate flux and solute rejection, presumably due to cake-enhanced concentration polarisation (CECP) effects. This review demonstrates why CECP effects are not always the reason behind the observed decline in the rejection of TOrCs by fouled membranes. To mitigate for fouling, researchers have often modified the membrane surfaces by incorporating nanoparticles. This review also attempts to explain why nano-engineered membranes have not seen a breakthrough at industrial scale. Finally, insight is provided into the possibility of harnessing solar and wind energy to drive energy intensive MSPs. Focus is also paid into how low-grade energy could be stored and applied to recover diluted draw solutions in FO mode.

Stereoselective profiling of methamphetamine in a full-scale wastewater treatment plant and its biotransformation in the activated sludge batch experiments

The stereoselective biotransformation of methamphetamine (METH), as a chiral compound, during biological treatment in wastewater treatment plants (WWTPs) is often ignored. In this study, a non-racemic form of METH was detected in the raw influent of a full-scale WWTP, with S-(+)-METH as the predominant enantiomer. Stereoselective biotransformation of METH in favor of S-(+)-METH occurred in anaerobic/anoxic and aerobic processes, resulting in the detection of R-(-)-METH as the only enantiomer in the secondary sedimentation tank. To evaluate the stereoselective biotransformation of METH in an activated sludge system, controlled laboratory experiments were conducted under aerobic and anaerobic conditions. Different stereoselective enrichment was observed in a racemic METH batch experiment at various initial concentrations. Batch experiment results with different initial concentrations of nutrient substances demonstrated that the biotransformation of S-(+)-METH occurred simultaneously with the biodegradation of COD and NH4+-N, proving its cometabolism nature. Enzymes released under microbial starvation stress likely stimulated R-(-)-METH biotransformation. Compared with the biotransformation rate of METH under the anaerobic condition, the presence of dissolved oxygen led to a higher biotransformation rate of METH under the aerobic condition.

Novel Fe3O4@metal-organic framework@polymer core-shell-shell nanospheres for fast extraction and specific preconcentration of nine organophosphorus pesticides from complex matrices

Herein, a novel core-shell-shell magnetic nanosphere denoted as Fe₃O₄@ZIF-8@polymer was fabricated by sequential in situ self-assembly and precipitation polymerization for effective magnetic solid-phase extraction of nine organophosphorus pesticides (OPPs) from river water, pear, and cabbage samples. The integrated Fe₃O₄@ZIF-8@polymer featured convenient magnetic separation property and excellent multi-target binding ability. More importantly, the functional polymer coating greatly improved the extraction performance of Fe₃O₄@ZIF-8 for OPPs, thus facilitating the simultaneous determination of trace OPP residues in real samples. The developed MPSE-LC-MS/MS method exhibited good linearity (R² ≥ 0.9991) over the concentration range of 0.2-200 µg L^-1, low limits of detection of 0.0002-0.005 μg L^-1 for river water and 0.006-0.185 μg kg^-1 for pear and cabbage, satisfactory precision with relative standard deviations ≤ 9.7% and accuracy with recoveries of 69.5-94.3%. These results highlight that the combination of polymers with MOFs has great potential to fabricate excellent adsorbents for high-throughput analysis of various contaminants in complex matrices.

Chiral separation of beta-blockers by high-performance liquid chromatography and determination of bisoprolol enantiomers in surface waters

Beta-blockers are chiral compounds with enantiomers that have different bioactivity, which means that while one is active, the other can be inactive or even harmful. Due to their high consumption and incomplete degradation in waste water, they may reach surface waters and affect aquatic organisms. To address this issue we developed a chromatographic method suitable for determining beta-blocker enantiomers in surface waters. It was tested on five beta-blockers (acebutolol, atenolol, bisoprolol, labetalol and metoprolol) and validated on bisoprolol enantiomers. Good enantioseparation of all analysed beta-blockers was achieved on the Chirobiotic V column with the mobile phase composed of methanol/acetic acid/triethylamine (100/0.20/0.15 v/v/v) at a flow rate of 0.5 mL/min and column temperature of 45 °C. Method proved to be linear in the concentration range from 0.075 µg/mL to 5 µg/mL, and showed good recovery. The limits of bisoprolol enantiomer detection were 0.025 µg/mL and 0.026 µg/mL and of quantification 0.075 µg/mL and 0.075 µg/mL. Despite its limitations, it seems to be a promising method for bisoprolol enantiomer analysis in surface water samples. Further research could focus on waste water analysis, where enantiomer concentrations may be high. Furthermore, transferring the method to a more sensitive one such as liquid chromatography coupled with tandem mass spectrometry and using ammonium acetate as the mobile phase additive instead of acetic acid and triethylamine would perhaps yield much lower limits of detection and quantification.

Simultaneous enantioselective analysis of illicit drugs in wastewater and surface water by chiral LC-MS/MS: A pilot study on a wastewater treatment plant and its receiving river

An enantioselective method for quantifying amphetamine-type chiral illicit drugs (CIDs) in wastewater and surface water was developed, validated, and applied to samples from a wastewater treatment plant (WWTP) and its effluent-receiving river in Beijing, China. Water samples were subjected to solid-phase extraction (SPE) and then quantified via liquid chromatography-tandem mass spectrometry. The enantioseparation of CIDs was performed with a CHIRALPAK CBH column. Chromatographic parameters, including mobile phase composition and flow rates, were tested to identify the satisfactory enantiomeric resolution. The SPE method was optimized by evaluating variables, including SPE cartridge types, extraction solvents, and solvent volumes. The Oasis HLB sorbent showed good performance with recoveries exceeding 60% and matrix effects ranging from -19.6% to 26.6% for most target enantiomers, except for norephedrine (NE), in three different aquatic matrixes. The established method was superior to previously reported methods and had a low limit of detection, low limit of quantification, and short runtime (<45 min). The repeatability and reproducibility of the method reached 19.1% and 17.8%, respectively. The method was successfully utilized to monitor the daily variations in CIDs in the influent, effluent, and effluent-receiving river of a WWTP in Beijing over 1 week. The common occurrence of 1 R,2 S-(-)-ephedrine (1 R,2 S-(-)-EPH), 1 S,2 S-(+)-pseudoephedrine (1 S,2 S-(+)-PEPH), R-(-)-methamphetamine (METH), and S-(+)-METH in wastewater samples was observed. Ephedrines (1 R,2 S-(-)-EPH and 1 S,2 S-(+)-PEPH) were the most abundant CIDs in the influent, effluent, upstream, and downstream samples with concentrations of 725.8 ± 181.2 ng/L, 22.9 ± 4.9 ng/L, 12.96 ± 0.79 ng/L, and 11.6 ± 6.7 ng/L, respectively. METH was detectable in most water samples and was present in excess in S-enantiomer form in the influent and in R-enantiomer form in the effluent and surface water. R-(-)-MDMA was detected at a concentration of up to 2.4 ng/L in the influent. The metabolites norketamine (NK), amphetamine(AMP), MDA, and NE were not detected in water samples given the low concentration of their parent drugs.

Enantiomeric determination of cathinones in environmental water samples by liquid chromatography-high resolution mass spectrometry

The enantiomeric determination of chiral drugs in the environment is of emerging concern since their enantiomers often exhibit stereoselectivity in environmental occurrence, fate and toxicity. In this study a method based on solid-phase extraction followed by chiral liquid chromatography and high-resolution mass spectrometry has been developed for the enantiomeric determination of a group of cathinones in river water and effluent wastewater. The enantioseparation was carried out using a Chiralpak CBH column in reversed-phase mode, and optimised by evaluating the effects of flow rate, buffer concentration and organic modifier. Under optimal conditions, good enantioseparations (R_s ≥1.2) were achieved for all the analytes. Two mixed-mode cation-exchange sorbents (Oasis WCX and Oasis MCX) in solid-phase extraction were evaluated in river water. Oasis MCX sorbent showed better performance with apparent recoveries ranging from 57 to 91% and matrix effect ranging from -10 to 15%. It is worth noting that a shifting of retention times and loss of enantioresolutions in environmental water samples was observed for all the analytes when the Oasis WCX sorbent was used. The method was validated with river water and effluent wastewater samples and its overall performance was satisfactory. The method quantification limits for all the analyte enantiomers ranged from 1.0 to 2.9 ng/L in river water, and from 2.3 to 6.0 ng/L in effluent wastewater. The repeatability and reproducibility values, expressed as% relative standard deviation (n = 5) were less than 15%. The method was then applied to the analysis of river water and effluent wastewater. The racemic methylone and methedrone (EF=0.49 and 0.46, respectively) were detected at low ng/L in some of the river water samples.

An improved drop casting electrochemical strategy for furosemide quantification in natural waters exploiting chemically reduced graphene oxide on glassy carbon electrodes

This work exploits the applicability of a chemically reduced graphene oxide (CRGO) modification on the electrochemical response of a glassy carbon electrode (GCE) for the first-time sensitive determination of furosemide in natural waters. The batch injection analysis (BIA) is proposed as an analytical method, where CRGO-GCE is coupled to a BIA cell for amperometric measurements. Acetate buffer (0.1 μmol L^-1, pH 5.2) was used as the background electrolyte. The modification provided an increase in sensitivity (0.024 μA/μmol L^-1), low limit of detection (0.7 μmol L^-1), RSD (< 4%), and broad linear range (1-600 μmol L^-1). Recovery tests performed in two different concentration ranges resulted in values between 89 and 99%. Recovery tests were performed and compared with high-performance liquid chromatography (HPLC) with UV-Vis detection using Student's t test at a 95% significance level, and no significant differences were found, confirming the accuracy of the method. The developed method is proven faster (169 h^-1) compared with the HPLC analysis (5 h^-1), also comparable with other flow procedures hereby described, offering a low-cost strategy suitable to quantify an emerging pharmaceutical pollutant. Graphical abstract.

A multi-residue method by supercritical fluid chromatography coupled with tandem mass spectrometry method for the analysis of chiral and non-chiral chemicals of emerging concern in environmental samples

This manuscript presents the development, validation and application of a multi-residue supercritical fluid chromatography coupled with tandem mass spectrometry method for the analysis of 140 chiral and non-chiral chemicals of emerging concern in environmental samples, with 81 compounds being fully quantitative, 14 semi-quantitative and 45 qualitative, validated according to European Medicine Agency (EMA) guidelines (European Medicines Agency 2019). One unified LC-MS method was used to analyse all analytes, which were split into three injection methods to ensure sufficient peak resolution. The unified method provided an average of 113% accuracy and 4.5% precision across the analyte range. Limits of detection were in the range of 35 pg L⁻¹–0.7 μg L⁻¹, in both river water and wastewater, with an average LOD of 33 ng L⁻¹. The method was combined with solid-phase extraction and applied in environmental samples, showing very good accuracy and precision, as well as excellent chromatographic resolution of a range of chiral enantiomers including beta-blockers, benzodiazepines and antidepressants. The method resulted in quantification of 75% of analytes in at least two matrices, and 56% in the trio of environmental matrices of river water, effluent wastewater and influent wastewater, enabling its use in monitoring compounds of environmental concern, from their sources of origin through to their discharge into the environment.

Enantiomeric Fractionation during Biotransformation of Chiral Pharmaceuticals in Recirculating Water-Sediment Test Flumes

Many organic contaminants entering the aquatic environment feature stereogenic structural elements that give rise to enantiomerism. While abiotic processes usually act identical on enantiomers, biotic processes, such as biodegradation often result in enantiomeric fractionation (EFr), i.e., the change of the relative abundance of enantiomers. Therefore, EFr offers the opportunity to differentiate biodegradation in complex environmental systems from abiotic processes. In this study, an achiral-chiral two-dimensional liquid chromatographic method for the enantioseparation of selected pharmaceuticals was developed. This method was then applied to determine the enantiomeric compositions of eight chiral pharmaceuticals in 20 water-sediment test flumes and test EFr as an indicator of biodegradation. While all eight substances were attenuated by at least 60%, five (atenolol, metoprolol, celiprolol, propranolol, and flecainide) displayed EFr. No EFr was observed for citalopram, fluoxetine, and venlafaxine despite almost complete attenuation (80 to 100%). Celiprolol, a barely studied β-blocker, revealed the most distinct EFr among all investigated substances; however, EFr varied considerably with biodiversity. Celiprolol-H2 was identified as a biological transformation product possibly formed by reduction of the celiprolol keto group through a highly regio- and enantioselective carbonyl reductase. While celiprolol-H2 was observed across all flumes, as expected, its formation was faster in flumes with high bacterial diversity where also EFr was highest. Overall, EFr and transformation product formation together served as good indicators of biological processes; however, the strong dependence of EFr on biodiversity limits its usefulness in complex environmental systems.

Multi-residue enantioselective determination of emerging drug contaminants in seawater by solid phase extraction and liquid chromatography-tandem mass spectrometry

This study proposes a new multi-residue enantioselective method for the determination of emerging drug contaminants in sea water by solid phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). To achieve satisfactory enantiomeric separation with a vancomycin stationary phase it was essential to limit sodium chloride in extracted samples to <1 μg per injection. This was achieved through a straightforward SPE method using a 50 mL water wash volume and analyte elution in acetonitrile. A Chiral-V enantioselective column (150 × 2.1 mm; 2.7 μm particle size) operated in polar ionic mode enabled simultaneous drug separations in 30 minutes. Analytes with enantioresolution ≥1 were the stimulants amphetamine and methamphetamine, the beta-agonist salbutamol, the beta-blockers propranolol, sotalol and acebutolol, the anti-depressants fluoxetine, venlafaxine, desmethylvenlafaxine and citalopram, and the antihistamine chlorpheniramine. Method quantitation limits were <10 ng L-1 and method trueness was 80-110% for most analytes. The method was applied to samples from the Forth and Clyde estuaries, Scotland. Chiral drugs were present at concentrations in the range 4-159 ng L-1 and several were in non-racemic form (enantiomeric fraction ≠ 0.50) demonstrating enantiomer enrichment. This emphasises the need for further enantiospecific drug exposure and effect studies in the marine environment.

Widespread monitoring of chiral pharmaceuticals in urban rivers reveals stereospecific occurrence and transformation

The present work aimed to discuss the enantiomeric occurrence of chiral pharmaceuticals including 5 parent compounds (PCs) metoprolol, propranolol, atenolol, venlafaxine and fluoxetine as well as 6 of their transformation products (TPs) in surface water in Beijing. Among which, 9 out of 11 were detected during the two sampling campaigns with N-O-Didesmethylvenlafaxine (NODDV) and α-hydroxymetoprolol confirmed in the catchment for the first time. Metoprolol acid (MTPA) was the most abundant up to 1508 ng L^-1, followed by metoprolol and O-desmethylvenlafaxine (ODV). Most compounds showed 100% detection frequency or nearly, while norfluoxetine (the main metabolite of fluoxetine) and 4-hydroxypropranololone (one TP of propranolol) were not detected. Metoprolol (MTP) and venlafaxine (VFX) did not vary significantly between two sampling periods with mean concentrations of 280.7 and 22.9 ng L^-1, respectively. Enantiomeric enrichment was observed for venlafaxine, metoprolol and NODDV, where R-venlafaxine was preferentially biotransformed than the S-form through O-desmethylation. Risk assessment indicated that fluoxetine and atenolol could pose harmful effects to aquatic organisms. This work provides enantiospecific profiles of pharmaceutically active compounds (PhACs), and extended the concept of applying the ratio of TPs vs. parent compound plus their enantiomeric traits for quantitative assessment of in situ biodegradation. Due to the considerable contribution by TPs (64% in present study) as well as the unexpected impacts from enantiomeric existence, the stereoselectivity of chiral pollutants during environmental process should be taken into account in future study. To the best of the authors' knowledge, it is the first comprehensive evaluation of chiral pharmaceuticals and transformation products at enantiomeric level in aquatic environment in China, which would facilitate better understanding of their environmental fate.

Application of enantiomeric fractions in environmental forensics: Uncertainties and inconsistencies

The assumption that only biological processes are enantioselective introduces challenges in the reliability of enantioselective analysis as a tool for discriminating biotic and abiotic processes in the environmental fate of chiral pollutants. Enantioselectivity does not depend on the nature of the fate process a chiral contaminant undergoes but on the interaction of the chiral contaminant with homochirality inducing external agents (e.g. chiral molecules, macromolecules or surfaces such as enzymes, blood plasma, proteins, chiral co-pollutants, humic acid and soil organominerals). The environmental behavior of a chiral contaminant is difficult to anticipate because the interactions between the chiral contaminants and the homochirality inducing external agents is often complex and strongly influenced by local environment conditions such as pH, redox conditions, organic carbon, organic nitrogen, humic acid, and redox conditions. Furthermore, the use of enantioselective analysis in environmental forensics depend on the adequate separation and accurate identification and quantification of the enantiomers of the chiral contaminant. Matrix effects, instrument effects, inadequate enantioselective separation, and poor quantification techniques introduce uncertainties in the determination of enantiomeric composition. Here we present the weaknesses of this assumption and recommend using enantiomeric fractions as chemical markers of biotransformation with caution. We recommend using stable isotopes, including abiotic controls to determine if enantioselective sorption occurs, and determining stability of enantiomers in solvent or at elevated temperatures to account for confounding factors arising from matrix effects, enantioselective abiotic processes, and enantiomerization due solvent and thermal lability of the chiral analyte, respectively to maintain the integrity of the utility of enantiomeric composition changes as an environmental forensics tool.

Simultaneous enantiomeric analysis of non-steroidal anti-inflammatory drugs in environment by chiral LC-MS/MS: A pilot study in Beijing, China

A simple, sensitive and quick method for direct simultaneous chiral analysis of frequently used non-steroidal anti-inflammatory drugs (NSAIDs) (ibuprofen, naproxen and flurbiprofen) in river water by HPLC-MS/MS was established and validated. Chromatographic parameters including the mobile phase composition, pH values, temperature and flow rates were optimized to obtain both satisfactory sensitivity and enantiomeric resolution (Rs≥ 1.0), which suggested the composition and pH values of mobile phase played crucial influence on enantioseparations. The method demonstrated its superiority compared with previous studies regarding to the low MQLs (1.1-37.1 ng/L) and short runtime (< 20 min), enabling quantitative enantiomeric determination of trace level of emerging contaminants in water. The environmental monitoring of receiving water (34 sites along rivers) in Beijing revealed ibuprofen was the most abundant, with mean concentration of 114.9 ng/L and detection frequency of 91%, naproxen was also detectable at all sites from < MQL-43.2 ng/L, both presenting an excess of the S-(+)-enantiomer. Therefore to better understand the ecological risk posed from the trace organic contaminants on the aquatic organisms, chiral pollutants need analyzed at the enantiomeric levels. This is the first to profile the enantiospecific occurrence of NSAIDs in surface water in Beijing, China. It could provide useful information on environmental behaviors of chiral pollutants and facilitate more accurate environmental risk assessment.

Enantioselective LC-MS/MS for anthropogenic markers of septic tank discharge

Households in rural locations utilize septic tanks for wastewater treatment and can cause surface water contamination. A new methodology was developed to help investigate the role septic tanks play in the dissemination of prescription and over-the-counter drugs, personal care products and stimulants in the aqueous environment. Simultaneous analysis of 16 chiral and achiral anthropogenic markers was achieved using a Chirobiotic V2^® enantioselective column in polar ionic mode. The optimized method achieved quantitation limits for 16 compounds in the range 0.001-2.9 μg L^-1 and 0.0002-0.43 μg L^-1 for septic tank effluent and stream water, respectively. Application of the method to samples collected in North East Scotland found caffeine to be ubiquitous in all samples studied suggesting it as a good indicator of septic tank discharge. In rural streams studied, concentrations of all prescription drugs investigated were ≤0.02 μg L^-1. However, analgesics and stimulants were at high concentration in one location indicating direct discharge of septic tank wastewater (i.e., not dissipated through a soak away). For example, paracetamol, cotinine and caffeine were measured at 1100 μg L^-1, 31 μg L^-1 and 200 μg L^-1, respectively, which is comparable to septic tank effluents. Furthermore, S(+)-amphetamine and R(-)-amphetamine were present in this stream sample at 0.20 and 0.27 μg L^-1. This corresponds to an enantiomeric fraction of 0.43, which is typical of untreated wastewaters in the UK. Findings illustrate further study on the diffuse impact of septic tanks to surface water is needed and can be supported using this new multi-residue enantioselective method.

Pharmaceuticals in freshwater aquatic environments: A comparison of the African and European challenge

Hundreds of tons of pharmaceutical compounds are annually dispensed and consumed worldwide. Pharmaceuticals are an important class of emerging environmental micropollutants: their presence in water bodies is an increasing environmental concern. The aim of this review paper is to provide a comprehensive review of the occurrence of pharmaceuticals in freshwater aquatic environments in the African and European context. A literature survey has been performed, resulting in 3024 data points related to environmental occurrence. The concentration levels of 71 pharmaceuticals were assessed. The top ten most frequently detected and quantified compounds in both continents were sulfamethoxazole, carbamazepine, diclofenac, trimethoprim, ibuprofen, naproxen, paracetamol (acetaminophen), ketoprofen, venlafaxine and clarithromycin. The maximum concentrations of 17β-estradiol, estriol, ciprofloxacin, sulfamethoxazole, paracetamol, naproxen reported in African aquatic environments were ~3140, ~20,000, ~125, ~100, ~215 and ~171 times higher, respectively, than the concentrations reported in European based studies. The variation in pharmaceutical consumption, partial removal of pharmaceuticals in wastewater treatment processes, and the direct discharge of livestock animal farm wastewater were identified among the major reasons for the observed differences. Several pharmaceuticals were found in aquatic environments of both continents in concentration levels higher than their ecotoxicity endpoints. In Europe, compounds such as diclofenac, ibuprofen, triclosan, sulfadimidine, carbamazepine and fluoxetine were reported in a concentration higher than the available ecotoxicity endpoints. In Africa, much more compounds reached concentrations more than the ecotoxicity endpoints, including diclofenac, ibuprofen, paracetamol, naproxen, ciprofloxacin, triclosan, trimethoprim, sulfamethoxazole, carbamazepine and fluoxetine, estriol and 17β-estradiol. Details for each therapeutic group are presented in this review.

Seasonal occurrence and fate of chiral pharmaceuticals in different sewage treatment systems in Hong Kong: Mass balance, enantiomeric profiling, and risk assessment

Concern about the presence of chiral pharmaceuticals in the environment from wastewater discharge is mounting. In this work, the occurrence and fate of atenolol, metoprolol, venlafaxine, and chloramphenicol, including 10 different stereoisomers, were investigated in sewage and sludge from diverse treatment processes in 4 sewage treatment plants (STPs) in Hong Kong via 4 sampling campaigns over a period of 2 years. The average amounts of individual pharmaceuticals entering the STPs ranged from 4.91 g/d to 6290 g/d, with sludge carrying much lower amounts than the discharged effluent. Mass balance analysis revealed that: larger quantities of these pharmaceuticals were released during the dry seasons, biodegradation was the primary removal mechanism for atenolol and chloramphenicol, and the removal via primary sedimentation and disinfection processes was insignificant (<30%). Selectivity toward R-(+)-atenolol, S-(-)-metoprolol, and R-(-)-venlafaxine was mostly found across secondary-treated effluent samples. Sold as an enantiopure pharmaceutical in R,R-para-form, chloramphenicol was preferentially eliminated after biological process. This is the first study on the occurrence of chloramphenicol enantiomers in the aquatic environment. Ecotoxicological assessment indicated that atenolol and metoprolol could pose risks to marine fish in effluent-receiving waters (i.e., the western waters and Victoria Harbor) of Hong Kong, while R-(+)-atenolol could pose a risk to protozoans five times higher than the S-(-)-enantiomer.

Simultaneous enantioselective determination of 22 chiral pesticides in fruits and vegetables using chiral liquid chromatography coupled with tandem mass spectrometry

This paper presents a novel multi-residue method for the enantioselective analysis of 22 chiral pesticides in cucumber, tomato, cabbage, grape, mulberry, apple and pear at enantiomeric levels. Pesticides were efficiently extracted by magnetic solid-phase extraction based on graphene as sorbent. Response surface methodology was used to assist the multivariable optimization. The perfect chiral separation of the enantiomers was achieved on a Chiralpak IG column within 47 min by reversed-phase liquid chromatography coupled with tandem mass spectrometry, which is a significant improvement to resolve a large group of chiral compounds under one set of conditions. The method was validated in terms of selectivity, linearity, sensitivity, trueness and precision, which all satisfy the requirement for pesticides residue analysis. The proposed method was successfully applied for monitoring the occurrence and enantiomeric composition of pesticides in different fruits and vegetables, demonstrating its applicability for the routine analysis of chiral pesticide residues in food samples.

A study through batch tests on the analytical determination and the fate and removal of methamphetamine in the biological treatment of domestic wastewater

Methamphetamine (MET) is one of the most used illicit drugs in Europe and is recognized as one of the Emerging Organic Micropollutants. It is discharged into the sewerage system from different sources and then enters the wastewater treatment plants. The present study aimed at providing a better knowledge of the fate of MET through the wastewater treatment plants. The study addressed two different issues: (1) optimization of the analytical methods for MET determination in both liquid and sludge phases, focusing on the effects of potentially interfering substances and (2) investigation on the behaviour of MET in the biological treatment process, with specific concern for the biomass activity at different drug concentrations. Results of the study on issue 1 highlighted that the applied analytical method for MET determination (UPLC-MS/MS) is affected by the main components of wastewater for about 9-23%, which is comparable with the uncertainties of the method (about ± 28%). The method showed also to be repeatable and reliable (recovery > 75%; repeatability < 10-15%; bias uncertainty < 30%), and relatively easy-to-use. Therefore, it can be considered suitable for measurements on routine base in the WWTPs. Batch tests conducted to address issue 2 showed total removal of 84, 90, and 96% at 50, 100, and 200 ng/L initial MET concentration, respectively, for a contact time of 6 h. The removal process was mainly ascribed to the biological activity of both heterotrophic and autotrophic bacteria. The pseudo first-order kinetic model provided the best fitting of the experimental data of the overall biological processes at all the tested concentrations. Furthermore, the respirometric tests showed that MET does not induce any inhibition. Adsorption of MET on activated sludge was always very low.

Trimeprazine is enantioselectively degraded by an activated sludge in ready biodegradability test conditions

A great number of available pharmaceuticals are chiral compounds. Although they are usually manufactured as racemic mixtures, they can be enantioselectively biodegraded as a result of microbial processes. In this paper, a biodegradability assay in similar conditions to those recommended in OECD tests of enantiomers of trimeprazine (a phenothiazine employed as a racemate) is carried out. Experiments were performed in batch mode using a minimal salts medium inoculated with an activated sludge (collected from a Valencian Waste Water Treatment Plant, WWTP) and supplemented with the racemate. The concentration of the enantiomers of trimeprazine were monitored by means of a chiral HPLC method using a cellulose-based chiral stationary phase and 0.5 M NaClO₄/acetonitrile (60:40, v/v) mobile phases. Experiments were performed at three concentration levels of the racemate. In parallel, the optical density at 600 nm (OD600) was measured to control the biomass growth and to connect it with enantioselectivity. The calculated enantiomeric fractions (EF) offer the first evidence of enantioselective biodegradation of trimeprazine. A simplified Monod equation was used as a curve fitting approach for concentration (S), biodegradation (BD), and for the first time, EF experimental data in order to expand the usefulness of the results. Precision studies on S (repeatability conditions) and, for the first time, EF (intermediate precision conditions) were also performed.

Identification of Enantiomeric Byproducts During Microalgae-Mediated Transformation of Metoprolol by MS/MS Spectrum Based Networking

Metoprolol (MPL) is a chiral β-blocker ubiquitously detected in various environments due to its low to moderate removal in wastewater treatment plants. This study was conducted to test the potential of using microalgae to degrade emerging contaminant MPL and to characterize the enantiomeric enrichment during MPL degradation by microalgae. The results showed that PO₄³⁻- P, NO₃⁻- N and MPL could be simultaneously removed in the synthetic effluent by the targeted microalgae species, indicating microalgae were promising in wastewater treatment. Stereoselectivity was observed during MPL degradation by microalgae, with R-form enrichment. A marginal linear relationship between MPL degradation and enantiomeric enrichment was observed, implying that the enantiomeric tool, used as a quantitative indicator of biodegradation, could possibly be applied in MPL degradation by microalgae. An efficient liquid chromatograph tandem high resolution mass spectrometry (LC-HRMS/MS) chiral analytical method was developed to identify transformation products (TPs). The results showed that MS/MS spectral similarity networking could be used as a powerful tool to quickly identify unknown TPs. A total of 6 pairs of chiral TPs were identified, among which two new TPs of MPL including hydroxy{4-[2-hydroxy-3-(isopropylamino)propoxy]phenyl}acetic acid (α-HMPLA) and 4-[2-Hydroxy-3-(isopropylamino)propoxy]benzaldehyde (DMPLD) were firstly reported, and proposed transformation pathways of MPL by microalgae were given. Considering the paired TPs detected and that the degradation of the two enantiomers followed first order kinetics, the two enantiomers likely had the same degradation mechanism.

Multi-residue enantiomeric analysis of 18 chiral pesticides in water, soil and river sediment using magnetic solid-phase extraction based on amino modified multiwalled carbon nanotubes and chiral liquid chromatography coupled with tandem mass spectrometry

This manuscript describes, for the first time, the multi-residue analysis of 18 chiral pesticides at enantiomeric levels in both environmental liquid (river water, influent and effluent wastewater) and solid matrices (agricultural soil, forestal soil and river sediment) based on magnetic solid-phase extraction (MSPE) and chiral liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Magnetic amino modified multiwalled carbon nanotubes (m-MWCNTs-NH₂) were prepared and firstly applied to adsorb pesticides from complex matrices. Response surface methodology (RSM) was applied to assist the multivariable optimization. The simultaneous enantioseparation of the chiral pesticides was performed on a Chiralpak IG column. Under the optimum conditions, the mean recoveries for pesticides enantiomers from the water matrices ranged from 81.1 to 106.3% with intra-day RSD of 2.1-11.9% and inter-day RSD of 2.6-12.7%; the mean recoveries for all enantiomers from the solid matrices ranged from 80.3 to 105.9% with intra-day RSD of 2.3-10.9% and inter-day RSD of 4.0-13.4%. Good linearity was achieved for all enantiomers with determination coefficients (r²) greater than 0.9912. Method quantification limits were below 2.04ng L^-1 in liquid matrices and below 0.50ng g^-1 in solid matrices. The developed method offered some advantages, such as simple operation, rapidity and high concentration factor. Therefore, it is suitable for monitoring the enantiomeric compositions of chiral pesticides in different environmental matrices.

Determination of nine pharmaceutical active compounds in surface waters from Paraopeba River Basin in Brazil by LTPE-HPLC-ESI-MS/MS

A simple, inexpensive, versatile, and environment-friendly extraction method, using low-temperature partitioning extraction (LTPE), was validated to quantify pharmaceutical-active compounds (PhACs) in surface water samples by high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The PhACs analyzed were acetaminophen, bezafibrate, diclofenac, diltiazem, fluconazole, linezolid, miconazole, ondansetron hydrochloride, and trimethoprim. The detection and quantification limits ranged from 0.15 to 12.30 ng L^-1 and 0.43 to 40.60 ng L^-1, respectively. Recovery rates ranged from 46 to 135%, and relative standard deviation (RSD%) varied between 0.49 and 6.13%. This method was applied to monitor water contamination by PhACs in the Paraopeba River Basin (PRB), Minas Gerais state, Brazil. All PhACs, except linezolid which was not detected, were found in PRB water samples in concentrations that ranged from 2.6 ng L^-1 to 2.62 μg L^-1.

Mass spectrometric strategies for the investigation of biomarkers of illicit drug use in wastewater

The analysis of illicit drugs in urban wastewater is the basis of wastewater-based epidemiology (WBE), and has received much scientific attention because the concentrations measured can be used as a new non-intrusive tool to provide evidence-based and real-time estimates of community-wide drug consumption. Moreover, WBE allows monitoring patterns and spatial and temporal trends of drug use. Although information and expertise from other disciplines is required to refine and effectively apply WBE, analytical chemistry is the fundamental driver in this field. The use of advanced analytical techniques, commonly based on combined chromatography-mass spectrometry, is mandatory because the very low analyte concentration and the complexity of samples (raw wastewater) make quantification and identification/confirmation of illicit drug biomarkers (IDBs) troublesome. We review the most-recent literature available (mostly from the last 5 years) on the determination of IDBs in wastewater with particular emphasis on the different analytical strategies applied. The predominance of liquid chromatography coupled to tandem mass spectrometry to quantify target IDBs and the essence to produce reliable and comparable results is illustrated. Accordingly, the importance to perform inter-laboratory exercises and the need to analyze appropriate quality controls in each sample sequence is highlighted. Other crucial steps in WBE, such as sample collection and sample pre-treatment, are briefly and carefully discussed. The article further focuses on the potential of high-resolution mass spectrometry. Different approaches for target and non-target analysis are discussed, and the interest to perform experiments under laboratory-controlled conditions, as a complementary tool to investigate related compounds (e.g., minor metabolites and/or transformation products in wastewater) is treated. The article ends up with the trends and future perspectives in this field from the authors' point of view. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 37:258-280, 2018.

Chiral Drug Analysis in Forensic Chemistry: An Overview

Many substances of forensic interest are chiral and available either as racemates or pure enantiomers. Application of chiral analysis in biological samples can be useful for the determination of legal or illicit drugs consumption or interpretation of unexpected toxicological effects. Chiral substances can also be found in environmental samples and revealed to be useful for determination of community drug usage (sewage epidemiology), identification of illicit drug manufacturing locations, illegal discharge of sewage and in environmental risk assessment. Thus, the purpose of this paper is to provide an overview of the application of chiral analysis in biological and environmental samples and their relevance in the forensic field. Most frequently analytical methods used to quantify the enantiomers are liquid and gas chromatography using both indirect, with enantiomerically pure derivatizing reagents, and direct methods recurring to chiral stationary phases.

Enantioselective transformation of fluoxetine in water and its ecotoxicological relevance

European legislation focusing on water quality is expected to broaden to encompass several pharmaceuticals as priority hazardous substances. This manuscript aims to challenge current regulatory approaches that do not recognize stereochemistry of chiral pharmaceuticals by testing the hypothesis that environmental transformation and effects of chiral pharmaceuticals are stereoselective. Our experiments revealed that, while degradation of chiral fluoxetine (FL) in river water occurs via non-enantioselective photochemical and mildly-enantioselective microbial processes favoring the (R)-enantiomer, a pronounced enantioselectivity favoring (S)-FL (leading to the formation of (S)-NFL (norfluoxetine)) is observed during activated sludge treatment. Toxicity tests proved strong enantiomer-specific toxicity in the case of Tetrahymena thermophila, protozoa that are utilized during activated sludge treatment ((R)-FL is 30× more toxic than (S)-FL; (S)-NFL is 10× more toxic than (S)-FL). This is of paramount importance as preferential degradation of (S)-FL in activated sludge microcosms leads to the enrichment of FL with 30× more toxic (R)-FL and formation of 10× more toxic (S)-NFL. It is commonly assumed that a decreased concentration of FL leads to decreased biological impact. Our study proves that despite the overall decrease in FL concentration, accumulation of toxic (R)-FL and formation of toxic (S)-NFL leads to much higher than presumed toxicological effects.

Chiral pharmaceuticals: A review on their environmental occurrence and fate processes

More than 50% of pharmaceuticals in current use are chiral compounds. Enantiomers of the same pharmaceutical have identical physicochemical properties, but may exhibit differences in pharmacokinetics, pharmacodynamics and toxicity. The advancement in separation and detection methods has made it possible to analyze trace amounts of chiral compounds in environmental media. As a result, interest on chiral analysis and evaluation of stereoselectivity in environmental occurrence, phase distribution and degradation of chiral pharmaceuticals has grown substantially in recent years. Here we review recent studies on the analysis, occurrence, and fate of chiral pharmaceuticals in engineered and natural environments. Monitoring studies have shown ubiquitous presence of chiral pharmaceuticals in wastewater, surface waters, sediments, and sludge, particularly β-receptor antagonists, analgesics, antifungals, and antidepressants. Selective sorption and microbial degradation have been demonstrated to result in enrichment of one enantiomer over the other. The changes in enantiomer composition may also be caused by biologically catalyzed chiral inversion. However, accurate evaluation of chiral pharmaceuticals as trace environmental pollutants is often hampered by the lack of identification of the stereoconfiguration of enantiomers. Furthermore, a systematic approach including occurrence, fate and transport in various environmental matrices is needed to minimize uncertainties in risk assessment of chiral pharmaceuticals as emerging environmental contaminants.

Enantioselective reductive transformation of climbazole: A concept towards quantitative biodegradation assessment in anaerobic biological treatment processes

An efficient chiral method-based using liquid chromatography-high resolution-mass spectrometry analytical method has been validated for the determination of climbazole (CBZ) enantiomers in wastewater and sludge with quantification limits below the 1 ng/L and 2 ng/g range, respectively. On the basis of this newly developed analytical method, the stereochemistry of CBZ was investigated over time in sludge biotic and sterile batch experiments under anoxic dark and light conditions and during wastewater biological treatment by subsurface flow constructed wetlands. CBZ stereoselective degradation was exclusively observed under biotic conditions, confirming the specificity of enantiomeric fraction variations to biodegradation processes. Abiotic CBZ enantiomerization was insignificant at circumneutral pH and CBZ was always biotransformed into CBZ-alcohol due to the specific and enantioselective reduction of the ketone function of CBZ into a secondary alcohol function. This transformation was almost quantitative and biodegradation gave good first order kinetic fit for both enantiomers. The possibility to apply the Rayleigh equation to enantioselective CBZ biodegradation processes was investigated. The results of enantiomeric enrichment allowed for a quantitative assessment of in situ biodegradation processes due to a good fit (R² > 0.96) of the anoxic/anaerobic CBZ biodegradation to the Rayleigh dependency in all the biotic microcosms and was also applied in subsurface flow constructed wetlands. This work extended the concept of applying the Rayleigh equation towards quantitative biodegradation assessment of organic contaminants to enantioselective processes operating under anoxic/anaerobic conditions.

Simultaneous enantiomeric analysis of pharmacologically active compounds in environmental samples by chiral LC-MS/MS with a macrocyclic antibiotic stationary phase

This paper presents a multi-residue method for direct enantioselective separation of chiral pharmacologically active compounds in environmental matrices. The method is based on chiral liquid chromatography and tandem mass spectrometry detection. Simultaneous chiral discrimination was achieved with a macrocyclic glycopeptide-based column with antibiotic teicoplanin as a chiral selector working under reverse phase mode. For the first time, enantioresolution was reported for metabolites of ibuprofen: carboxyibuprofen and 2-hydroxyibuprofen with this chiral stationary phase. Moreover, enantiomers of chloramphenicol, ibuprofen, ifosfamide, indoprofen, ketoprofen, naproxen and praziquantel were also resolved. The overall performance of the method was satisfactory in terms of linearity, precision, accuracy and limits of detection. The method was successfully applied for monitoring of pharmacologically active compounds at enantiomeric level in influent and effluent wastewater and in river water. In addition, the chiral recognition and analytical performance of the teicoplanin-based column was critically compared with that of the α₁ -acid glycoprotein chiral stationary phase. Copyright © 2017 John Wiley & Sons, Ltd.

Chromatographic Studies of Protein-Based Chiral Separations

The development of separation methods for the analysis and resolution of chiral drugs and solutes has been an area of ongoing interest in pharmaceutical research. The use of proteins as chiral binding agents in high-performance liquid chromatography (HPLC) has been an approach that has received particular attention in such work. This report provides an overview of proteins that have been used as binding agents to create chiral stationary phases (CSPs) and in the use of chromatographic methods to study these materials and protein-based chiral separations. The supports and methods that have been employed to prepare protein-based CSPs will also be discussed and compared. Specific types of CSPs that are considered include those that employ serum transport proteins (e.g., human serum albumin, bovine serum albumin, and alpha1-acid glycoprotein), enzymes (e.g., penicillin G acylase, cellobiohydrolases, and α-chymotrypsin) or other types of proteins (e.g., ovomucoid, antibodies, and avidin or streptavidin). The properties and applications for each type of protein and CSP will also be discussed in terms of their use in chromatography and chiral separations.

Characterization of pharmaceutically active compounds in Dongting Lake, China: Occurrence, chiral profiling and environmental risk

Twenty commonly used pharmaceuticals including eight chiral drugs were investigated in Dongting Lake, China. The contamination level was relatively low on a global scale. Twelve pharmaceuticals were identified. The most abundant compound was caffeine followed by diclofenac, DEET, mefenamic acid, fluoxetine, ibuprofen and carbamazepine with mean concentrations from 2.0 to 80.8ngL(-1). Concentrations between East and West Dongting Lake showed spatial difference, with the West Dongting Lake less polluted. The relatively high ratio of caffeine versus carbamazepine (over 50) may indicate there was possible direct discharge of domestic wastewater into the lake. This is the first study presenting a survey allowing for comprehensive analysis of multiclass achiral and chiral pharmaceuticals including beta-blockers, antidepressants and anti-inflammatory drugs in freshwater lake. The enantiomeric compositions presented racemic to weakly enantioselective, with the highest enantiomeric fraction (EF) of 0.63 for fluoxetine. Meanwhile, venlafaxine was identified and evaluated the environment risk in surface water in China for the first time. The results of risk assessment suggested that fluoxetine, venlafaxine and diclofenac acid might pose a significant risk to aquatic organisms in Dongting Lake. The resulting data will be useful to enrich the research of emerging pollutants in freshwater lake and stereochemistry for environment investigations.

Enantiomeric Profiling of Chiral Pharmacologically Active Compounds in the Environment with the Usage of Chiral Liquid Chromatography Coupled with Tandem Mass Spectrometry

The issue of drug chirality is attracting increasing attention among the scientific community. The phenomenon of chirality has been overlooked in environmental research (environmental occurrence, fate and toxicity) despite the great impact that chiral pharmacologically active compounds (cPACs) can provoke on ecosystems. The aim of this paper is to introduce the topic of chirality and its implications in environmental contamination. Special attention has been paid to the most recent advances in chiral analysis based on liquid chromatography coupled with mass spectrometry and the most popular protein based chiral stationary phases. Several groups of cPACs of environmental relevance, such as illicit drugs, human and veterinary medicines were discussed. The increase in the number of papers published in the area of chiral environmental analysis indicates that researchers are actively pursuing new opportunities to provide better understanding of environmental impacts resulting from the enantiomerism of cPACs.

Enantiomeric fractionation as a tool for quantitative assessment of biodegradation: The case of metoprolol

An efficient chiral liquid chromatography high resolution mass spectrometry method has been developed for the determination of metoprolol (MTP) and three of its major metabolites, namely O-desmethylmetoprolol (O-DMTP), α-hydroxymetoprolol (α-HMTP) and metoprolol acid (MTPA) in wastewater treatment plant (WWTP) influents and effluents. The optimized analytical method has been validated with good quality parameters including resolution >1.3 and method quantification limits down to the ng/L range except for MTPA. On the basis of this newly developed analytical method, the stereochemistry of MTP and its metabolites was studied over time in effluent/sediment biotic and sterile microcosms under dark and light conditions and in influents and effluents of 5 different WWTPs. MTP stereoselective degradation was exclusively observed under biotic conditions, confirming the specificity of enantiomeric fraction variations to biodegradation processes. MTP was always biotransformed into MTPA with a (S)-enantiomer enrichment. The results of enantiomeric enrichment pointed the way for a quantitative assessment of in situ biodegradation processes due to a good fit (R(2) > 0.98) of the aerobic MTP biodegradation to the Rayleigh dependency in all the biotic microcosms and in WWTPs because both MTP enantiomers followed the same biodegradation kinetic profiles. These results demonstrate that enantiomeric fractionation constitutes a very interesting quantitative indicator of MTP biodegradation in WWTPs and probably in the environment.

Applicability of the Rayleigh equation for enantioselective metabolism of chiral xenobiotics by microsomes, hepatocytes and in-vivo retention in rabbit tissues

In this study we propose a new approach for analyzing the enantioselective biodegradation of some antidepressant drugs mediated by human and rat liver microsomes by using the Rayleigh equation to describe the enantiomeric enrichment−conversion dependencies. Analysis of reported degradation data of additional six pesticides, an alpha blocker and a flame retardant by microsomes or hepatocytes in vitro reaffirmed the universality of the approach. In all the in vitro studied cases that involved enantioselective degradation, a Rayleigh dependence of the enantiomeric enrichment was observed. Published data regarding in vivo retention of myclobutanil in liver, kidney, muscle and brain tissues of rabbits following injection of the racemate were remodeled showing prevalence of the Rayleigh law for the chiral enrichment of the fungicide in the various tissues. This approach will revolutionize data organization in metabolic pathway research of target xenobiotics by either liver microsomes, hepatocytes or their organ-specific in vivo retention. The fact that the enantiomeric enrichment as a function of the conversion can be described by a single quantifier, will pave the road for the use of structure activity predictors of the enantiomeric enrichment and for mechanistic discrimination based on parametric dependence of the quantifier.

Multi-residue enantiomeric analysis of human and veterinary pharmaceuticals and their metabolites in environmental samples by chiral liquid chromatography coupled with tandem mass spectrometry detection

Enantiomeric profiling of chiral pharmacologically active compounds (PACs) in the environment has hardly been investigated. This manuscript describes, for the first time, a multi-residue enantioselective method for the analysis of human and veterinary chiral PACs and their main metabolites from different therapeutic groups in complex environmental samples such as wastewater and river water. Several analytes targeted in this paper have not been analysed in the environment at enantiomeric level before. These are aminorex, carboxyibuprofen, carprofen, cephalexin, 3-N-dechloroethylifosfamide, 10,11-dihydro-10-hydroxycarbamazepine, dihydroketoprofen, fenoprofen, fexofenadine, flurbiprofen, 2-hydroxyibuprofen, ifosfamide, indoprofen, mandelic acid, 2-phenylpropionic acid, praziquantel and tetramisole. The method is based on chiral liquid chromatography utilising a chiral α1-acid glycoprotein column and tandem mass spectrometry detection. Excellent chromatographic separation of enantiomers (Rs≥1.0) was achieved for chloramphenicol, fexofenadine, ifosfamide, naproxen, tetramisole, ibuprofen and their metabolites: aminorex and dihydroketoprofen (three of four enantiomers), and partial separation (Rs = 0.7-1.0) was achieved for ketoprofen, praziquantel and the following metabolites: 3-N-dechloroethylifosfamide and 10,11-dihydro-10-hydroxycarbamazepine. The overall performance of the method was satisfactory for most of the compounds targeted. Method detection limits were at low nanogram per litre for surface water and effluent wastewater. Method intra-day precision was on average under 20% and sample pre-concentration using solid phase extraction yielded recoveries >70% for most of the analytes. This novel, selective and sensitive method has been applied for the quantification of chiral PACs in surface water and effluent wastewater providing excellent enantioresolution of multicomponent mixtures in complex environmental samples. It will help with better understanding of the role of individual enantiomers in the environment and will enable more accurate environmental risk assessment.

Selective serotonin reuptake inhibitors and β-blocker transformation products may not pose a significant risk of toxicity to aquatic organisms in wastewater effluent-dominated receiving waters

A probabilistic ecological risk assessment was conducted for the transformation products (TPs) of 3 β-blockers (atenolol, metoprolol, and propranolol) and 5 selective serotonin reuptake inhibitors (SSRIs; citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline) to assess potential threats to aquatic organisms in effluent-dominated surface waters. To this end, the pharmacokinetic literature, the University of Minnesota's Biocatalysis/Biodegradation Database Pathway Prediction System aerobic microbial degradation software, and photolysis literature pertaining to β-blockers and SSRIs were used to determine their most likely TPs formed via human metabolism, aerobic biodegradation, and photolysis, respectively. Monitoring data from North American and European surface waters receiving human wastewater inputs were the basis of the exposure characterizations of the parent compounds and the TPs, where available. In most cases, where monitoring data for TPs did not exist, we assumed a conservative 1:1 parent-to-TP production ratio (i.e., 100% of parent converted). The US Environmental Protection Agency (USEPA)'s EPISuite and ECOSAR v1.11 software were used to estimate acute and chronic toxicities to aquatic organisms. Hazard quotients, which were calculated using the 95(th) percentile of the exposure distributions, ranged from 10(-11) to 10(-3) (i.e., all significantly less than 1). Based on these results, the TPs of interest would be expected to pose little to no environmental risk in surface waters receiving wastewater inputs. Overall, we recommend developing analytical methods that can isolate and quantify human metabolites and TPs at environmentally relevant concentrations to confirm these predictions. Further, we recommend identifying the major species of TPs from classes of pharmaceuticals that could elicit toxic effects via specific modes of action (e.g., norfluoxetine via the serotonin 5-hydroxytryptamine [5-HT]1A receptors) and conducting aquatic toxicity tests to confirm these findings. To our knowledge, this is the first quantitative probabilistic ecotoxicological assessment of all of the predicted and probable TPs of these pharmaceuticals, and our approach provides a framework for future such studies with other compound classes as data become available.

A review on emerging contaminants in wastewaters and the environment: current knowledge, understudied areas and recommendations for future monitoring

This review identifies understudied areas of emerging contaminant (EC) research in wastewaters and the environment, and recommends direction for future monitoring. Non-regulated trace organic ECs including pharmaceuticals, illicit drugs and personal care products are focused on due to ongoing policy initiatives and the expectant broadening of environmental legislation. These ECs are ubiquitous in the aquatic environment, mainly derived from the discharge of municipal wastewater effluents. Their presence is of concern due to the possible ecological impact (e.g., endocrine disruption) to biota within the environment. To better understand their fate in wastewaters and in the environment, a standardised approach to sampling is needed. This ensures representative data is attained and facilitates a better understanding of spatial and temporal trends of EC occurrence. During wastewater treatment, there is a lack of suspended particulate matter analysis due to further preparation requirements and a lack of good analytical approaches. This results in the under-reporting of several ECs entering wastewater treatment works (WwTWs) and the aquatic environment. Also, sludge can act as a concentrating medium for some chemicals during wastewater treatment. The majority of treated sludge is applied directly to agricultural land without analysis for ECs. As a result there is a paucity of information on the fate of ECs in soils and consequently, there has been no driver to investigate the toxicity to exposed terrestrial organisms. Therefore a more holistic approach to environmental monitoring is required, such that the fate and impact of ECs in all exposed environmental compartments are studied. The traditional analytical approach of applying targeted screening with low resolution mass spectrometry (e.g., triple quadrupoles) results in numerous chemicals such as transformation products going undetected. These can exhibit similar toxicity to the parent EC, demonstrating the necessity of using an integrated analytical approach which compliments targeted and non-targeted screening with biological assays to measure ecological impact. With respect to current toxicity testing protocols, failure to consider the enantiomeric distribution of chiral compounds found in the environment, and the possible toxicological differences between enantiomers is concerning. Such information is essential for the development of more accurate environmental risk assessment.