Method validation for the analysis of estrogens (including conjugated compounds) in aqueous matrices

Comparison of Trace Organic Chemical Removal Efficiencies between Aerobic and Anaerobic Membrane Bioreactors Treating Municipal Wastewater

Evaluating persistent trace organic chemicals (TOrCs) and transformation products (TPs) in membrane bioreactors (MBRs) is essential, given that MBRs are now widely implemented for wastewater treatment and water reuse. This research applied comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC/TOF-MS)-based nontargeted analysis to compare the effectiveness of parallel aerobic and anaerobic MBRs (AeMBRs and AnMBRs, respectively), treating the same municipal wastewater. The average total chromatographic feature peak area abundances were significantly reduced by 84% and 72% from influent to membrane permeate in both the AeMBR and AnMBR (p < 0.05), respectively. However, the reduction of the average number of chromatographic features was significant for only AeMBR treatment (p = 0.006). A similar number of TPs were generated during both AeMBR and AnMBR treatments (165 vs 171 compounds, respectively). The overall results suggest that the AeMBR was more effective for reducing the diversity of TOrCs than the AnMBR, but both aerobic and anaerobic processes had a similar reduction of TOrC abundance. Suspect screening analysis using GC×GC/TOF-MS, which resulted in the tentative identification of 351 TOrCs, proved to be a powerful approach for uncovering compounds previously unreported in wastewater, including many fragrances and personal care products.

Summary recommendations on "Analytical methods for substances in the Watch List under the Water Framework Directive"

The Watch List (WL) is a monitoring program under the European Water Framework Directive (WFD) to obtain high-quality Union-wide monitoring data on potential water pollutants for which scarce monitoring data or data of insufficient quality are available. The main purpose of the WL data collection is to determine if the substances pose a risk to the aquatic environment at EU level and subsequently to decide whether a threshold, the Environmental Quality Standards (EQS) should be set for them and, potentially to be listed as priority substance in the WFD. The first WL was established in 2015 and contained 10 individual or groups of substances while the 4th WL was launched in 2022. The results of monitoring the substances of the first WL showed that some countries had difficulties to reach an analytical Limit of Quantification (LOQ) below or equal to the Predicted No-Effect Concentrations (PNEC) or EQS. The Joint Research Centre (JRC) of the European Commission (EC) organised a series of workshops to support the EU Member States (MS) and their activities under the WFD. Sharing the knowledge among the Member States on the analytical methods is important to deliver good data quality. The outcome and the discussion engaged with the experts are described in this paper, and in addition a literature review of the most important publications on the analysis of 17-alpha-ethinylestradiol (EE2), amoxicillin, ciprofloxacin, metaflumizone, fipronil, metformin, and guanylurea from the last years is presented.

Occurrence and environmental risk assessment of 4 estrogenic compounds in surface water in Belgium in the frame of the EU Watch List

The presence of natural estrogens estrone (E1), 17β-estradiol (E2), estriol (E3) and synthetic estrogen 17α-ethynylestradiol (EE2) in the aquatic environment has raised concerns because of their high potency as endocrine disrupting chemicals. The European Commission (EC) established a Watch List of contaminants of emerging concerns including E1, E2 and EE2. The proposed environmental quality standards (EQSs) are 3.6, 0.4, 0.035 ng/L, for E1, E2, EE2, respectively. A thorough evaluation of analytical procedures developed by several studies aiming to perform sampling campaigns in different European countries highlighted that the required limits of quantification in surface water were not reached, especially for EE2 and to a lesser extent for E2. Moreover, data regarding the occurrence of these contaminants in Belgian surface water are very limited. A sampling campaign was therefore performed on a wide range of rivers in Belgium (accounting for a total of 63 samples). The detection frequencies of E1, E2, E3 and EE2 were 100, 98, 86 and 48%, respectively. E1 showed the highest mean concentration (= 4.433 ng/L). In contrast, the mean concentration of EE2 was 0.042 ng/L. The risk quotients (RQs) were calculated based on the respective EQS of each analyte. The frequency of exceedance of the EQS was 31.7% for E1, EE2, while it increased to 44.4% for E2. The extent of exceedance of the EQS, represented by the 95th percentile of the RQ dataset, was higher than 1 for E1, E2, EE2. The use of a confusion matrix was investigated to try to predict the risk posed by E2, EE2, based on the concentration of E1.

Development and implementation of an analytical procedure for the quantification of natural and synthetic steroid hormones in whole surface waters

Natural and synthetic steroid hormones are chronically released into aquatic spheres. Whereas knowledge on their combined mode of action and the cocktail effect are needed, only few multi-class methods address the challenge of their trace quantification in surface waters. The current study describes a sensitive multi-residue analytical strategy aiming to quantify 23 steroid hormones belonging to androgens, estrogens, glucocorticoids and progestogens in whole surface waters. The procedure relies on a two-step solid-phase extraction followed by an ultra-performance liquid chromatography separation coupled to tandem mass spectrometry detection (UPLC-MS/MS). Isotope dilution was implemented when possible in order to ensure the reliability of the measurement. The procedure was optimized toward the reliable quantification of the 23 target compounds at the predicted no-effect concentrations when existing or below the ng L^-1 level. Satisfactory absolute global recoveries ≥ 77% were obtained for almost all compounds (21 out of 23) in intermediate precision conditions. Measurement errors were comprised between -27% and +17% for the great majority of compounds (21 out of 23) with standard deviations < 20% in intermediate precision conditions. Despite signal suppression was observed in water samples, satisfactory limits of quantification were achieved, ranging from 0.035 ng L^-1 for 17alpha-ethinylestradiol to 1 ng L^-1 for 6beta-hydroxycortisol and 6beta-hydroxydexamethasone. Abiotic stability was demonstrated for the great majority of target compounds (22 out of 23) in reference water samples stored at 4 ± 3 °C during 48 h, driving our sampling strategy. To demonstrate its fitness for purpose, the procedure was implemented in a preliminary monitoring survey of Belgian surface waters. As a result, 6 out of 23 target compounds were detected or quantified, showing a contamination by some estrogens and glucocorticoids at levels ranging from 0.1 to 0.9 ng L^-1.

Separation and degradation detection of nanogram-per-litre concentrations of radiolabelled steroid hormones using combined liquid chromatography and flow scintillation analysis

Detection of micropollutants such as steroid hormones occurring in the aquatic environment at concentrations between ng/L and µg/L remains a major challenge, in particular when treatment efficiency is to be evaluated. Steroid hormones are typically analysed using mass-spectrometry methods, requiring pre-concentration and/or derivatisation procedures to achieve required detection limits. Free of sample preparation steps, the use of radiolabelled contaminants with liquid scintillation counting is limited to single-compound systems and require a separation of hormone mixtures before detection. In this work, a method was developed coupling ultra-high-pressure liquid chromatography (UHPLC) with flow scintillation analysis (FSA) for separation and detection of radiolabelled estrone, 17ß-estradiol, testosterone and progesterone. Adjustment of the flow rate of scintillation liquid and UHPLC mobile phase, gradient time, column temperature, and injection volume allowed the separation of steroid hormones and degradation products. The limit-of-detection (LOD = 1.5–2.4 ng/L) and limit-of-quantification (LOQ = 3.4–4.3 ng/L) for steroid hormones were comparable with the current state-of-the-art technique (LC-MS/MS) for non-derivatised compounds. Although the method cannot be applied to real water samples (unless spiked with radiotracers), it serves as a useful tool for the development of water treatment technologies at laboratory scale as demonstrated via: i) adsorption on polymer-based spherical activated carbon, ii) retention in nanofiltration, iii) photodegradation using a photocatalytic membrane.

Simultaneous UHPLC-MS/MS method of estradiol metabolites to support the evaluation of Phase-2 metabolic activity of induced pluripotent stem cell derived hepatocytes

The goal of this study was to develop and validate a high-throughput UHPLC-MS/MS method for simultaneous quantitation of three estradiol metabolites namely estradiol 3-β-D-glucuronide (E3G), estradiol 17-β-D-glucuronide (E17G) and estradiol 3-sulfate (E3S) in cell culture medium to support the characterization of metabolic function of induced pluripotent stem cell (iPSC) derived hepatocytes. To achieve this goal, a simple protein precipitation method was used for sample cleanup. All the metabolites were separated chromatographically using a C-18 column where 10 mM ammonium acetate and acetonitrile was used in gradient flow for 4 min. The analytes were quantitated by triple quadrupole mass spectrometer with the use of isotopically labeled internal standard (IS). This method was validated as per the U.S Food and Drug Administration's Bioanalytical Method Validation, Guidance for Industry. Linearity for E3G and E17G was in the range of 2-1500 ng/mL whereas for E3S it was 0.3-500 ng/mL. Inter-day and intra-day accuracy and precision of this method were in the acceptable limits. In addition, multiple stability tests (freeze thaw, autosampler, water bath (37 °C), bench top and long term) were performed for all the metabolites in cell culture medium. All the metabolites were stable up to 3 freeze thaw cycles at -20 °C and - 80 °C, 48 h in autosampler, 24 h at 37 °C, 48 h at room temperature and 173 days at -20 °C. Extraction recoveries for the metabolites were reproducible and were in the range of 94-108%. This method was used to quantitate estradiol metabolites generated by iPSC hepatocytes in-vitro studies.

Kinetic accumulation processes and models for 43 micropollutants in "pharmaceutical" POCIS

The "pharmaceutical" polar organic integrative sampler (POCIS) is a passive sampler composed of an outer polyethersulfone (PES) membrane and an inner receiving Hydrophilic-Lipophilic Balance (HLB) phase. Target micropollutants can accumulate in the POCIS HLB phase following different uptake patterns. Two of the most common ones are a first-order kinetic uptake (Chemical Reaction Kinetic 1, CRK1 model), and a first-order kinetic uptake with an inflexion point (CRK2 model). From a previous study, we identified 30 and 13 micropollutants following CRK1 and CRK2 accumulation model in the POCIS HLB phase, respectively. We hypothesized that uptake in the outer PES membrane of POCIS may influence the uptake pathway. Thus, novel measurements of uptake in PES membrane were performed for these micropollutants to characterise kinetic accumulation in the membrane with and without the HLB phase. We determined, for the first time, the membrane-water distribution coefficient for 31 micropolluants. Moreover, the lag times for molecules to breakthrough the POCIS membrane increased with increasing hydrophobicity, defined by the octanol-water dissociation constant D_ow. However, D_ow alone was insufficient to predict whether uptake followed a CRK1 or CRK2 model in the POCIS HLB phase. Thus, we performed a factorial discriminant analysis considering several molecular physico-chemical properties, and the model of accumulation for the studied micropollutants can be predicted with >90% confidence. The most influent properties to predict the accumulation model were the log D_ow and the polar surface area of the molecule (>70% confidence with just these two properties). Molecules exhibiting a CRK1 uptake model for the POCIS HLB phase tended to have log D_ow>2.5 and polar surface area <50Ǻ².

Quality survey of natural mineral water and spring water sold in France: Monitoring of hormones, pharmaceuticals, pesticides, perfluoroalkyl substances, phthalates, and alkylphenols at the ultra-trace level

The aim of the present study, one of the most complete ever performed in France, was to carry out an extensive survey on the potential presence of a large amount of emerging contaminants in 40 French bottled waters, including parent compounds and metabolites. The studied samples represented 70% of the French bottled water market in volume. Six classes of compounds were investigated, most of them being unregulated in bottled waters: pesticides and their transformation products (118), pharmaceutical substances (172), hormones (11), alkylphenols (APs) (8), phthalates (11) and perfluoroalkyl substances (PFAS) (10). One of the objectives of this work was to achieve low and reliable limits of quantification (LOQs) (87% of the LOQs were below 10ng/L) using advanced analytical technologies and reliable sample preparation methodologies, including stringent quality controls. Among the 14,000 analyses performed, 99.7% of the results were below the LOQs. None of the hormones, pharmaceutical substances and phthalates were quantified. Nineteen compounds out of the 330 investigated were quantified in 11 samples. Eleven were pesticides including 7 metabolites, 6 were PFAS and 2 were APs. As regards pesticides, their sum was at least twice lower than the quality standards applicable for bottled waters in France. The presence of a majority of pesticide metabolites suggested a former use in the recharge areas of the exploited aquifers. The quantification of a few unregulated emerging compounds at the nano-trace level, such as PFAS, raised the issue of their potential sources, including long-range atmospheric transport and deposition. This study confirmed that the groundwater aquifers exploited for bottling were well-preserved from chemicals, as compared to less geologically protected groundwaters, and also underlined the need to pursue the protection policies implemented in recharge areas in order to limit the anthropogenic pressure.

Steroid hormones in environmental matrices: extraction method comparison

The U.S. Environmental Protection Agency (EPA) has developed methods for the analysis of steroid hormones in water, soil, sediment, and municipal biosolids by HRGC/HRMS (EPA Method 1698). Following the guidelines provided in US-EPA Method 1698, the extraction methods were validated with reagent water and applied to municipal wastewater, surface water, and municipal biosolids using GC/MS/MS for the analysis of nine most commonly detected steroid hormones. This is the first reported comparison of the separatory funnel extraction (SFE), continuous liquid-liquid extraction (CLLE), and Soxhlet extraction methods developed by the U.S. EPA. Furthermore, a solid phase extraction (SPE) method was also developed in-house for the extraction of steroid hormones from aquatic environmental samples. This study provides valuable information regarding the robustness of the different extraction methods. Statistical analysis of the data showed that SPE-based methods provided better recovery efficiencies and lower variability of the steroid hormones followed by SFE. The analytical methods developed in-house for extraction of biosolids showed a wide recovery range; however, the variability was low (≤ 7% RSD). Soxhlet extraction and CLLE are lengthy procedures and have been shown to provide highly variably recovery efficiencies. The results of this study are guidance for better sample preparation strategies in analytical methods for steroid hormone analysis, and SPE adds to the choice in environmental sample analysis.

Rethinking micropollutant removal assessment methods for wastewater treatment plants - how to get more robust data?

This paper covers the pitfalls, recommendations and a new methodology for assessing micropollutant removal efficiencies in wastewater treatment plants. The proposed calculation rules take into account the limit of quantification and the analytical and sampling uncertainty of measured concentrations. We identified six cases for which a removal efficiency value is reliable and four other cases where result is highly variable (uncertain) due to very low or unquantified concentrations in effluent or when the influent-effluent concentrations differential is below the measurement uncertainty. The influence of the proposed calculation rules on removal efficiency values was scrutinized using actual results from a research project. The paper arrives at detailed recommendations for limiting the impact of other sources of uncertainty during sampling (sampling strategy, cleaning and field blank), chemical analyses (suspended solids and sludge) and data processing according to the targeted objectives.

An ultrahigh-performance chromatography/tandem mass spectrometry quantitative method for trace analysis of potential endocrine disrupting steroid hormones in estuarine sediments

RATIONALE

Estuaries are dynamic ecosystems, providing vital habitat for unique organisms of great ecological and commercial importance. The influx of natural and synthetic steroid hormones into estuaries poses risks to these organisms and to broader ecosystem health. However, detecting these trace level pollutants in estuarine water and sediment requires improved analytical techniques.

METHODS

We describe an optimized ultrahigh-performance chromatography/tandem mass spectrometry (UHPLC/MS/MS) method for simultaneous quantitation of four classes of steroid hormones (estrogens, glucocorticoids, androgens and progestins) in sediment samples collected from an Alabama estuary. Sediment samples were homogenized using Hydromatrix (HM) sorbent and extracted with methanol and water (70%, v/v). Centrifuged extracts were purified using an Agilent Bond Elut QuEChERS dispersive-SPE kit to eliminate interfering substances that could negatively influence the ionization process. Chromatographic separation was achieved on a Poroshell 120 Phenyl-Hexyl column using an Agilent 1290 Infinity II UHPLC pump. Quantitation was carried out using an Agilent triple quadrupole mass spectrometer equipped with a JetStream/ESI source in dual mode.

RESULTS

Chromatographic separation and better peak resolution were accomplished on an Agilent Poroshell 120 Phenyl-Hexyl column using a binary gradient method with a mobile phase consisting of 1 mM ammonium fluoride in water and a mixture of methanol/acetonitrile. A dynamic multiple reaction monitoring (MRM) method was developed by optimizing various MS parameters. The method was used to analyze target steroid hormones in estuarine sediments. A total of ten steroid hormones were detected at trace amounts in estuarine sediments.

CONCLUSIONS

The optimized analytical method described here involves reasonably simple sample preparation and simultaneous trace level quantitation of four classes (estrogens, glucocorticoids, androgens and progestins) of steroid hormones in a single experimental run. Copyright © 2016 John Wiley & Sons, Ltd.

An Ultrasensitive (Parts-Per-Quadrillion) and SPE-Free Method for the Quantitative Analysis of Estrogens in Surface Water

An analytical method is presented here that is sensitive to the parts-per-quadrillion (pg/L) for estrogens in surface water. The estrogens included for study were estrone, 17β-estradiol, estriol, 17α-ethinylestradiol, and equilin. The method consisted of the small-scale liquid-liquid extraction of surface water followed by derivation with dansyl chloride. Analyte separation and detection were performed by high-pressure liquid-chromatography and tandem mass-spectrometry. A large volume (100 μL) of the sample was injected on-column to increase the analyte mass sent to the detector. The detection limits of the method were 0.045 ng/L for estrone, 0.086 ng/L for 17β-estradiol, 0.030 ng/L for estriol, 0.049 ng/L for 17α-ethinylestradiol, and 0.13 ng/L for equilin. The whole-method accuracy ranged from 93 ± 5.8% to 105 ± 4.5% for all the analytes at two different spike levels. Similarly, the precision of the method was less than 8.0% relative standard deviation. The final method was used to analyze a series of samples from the Mississippi River spanning 51 river miles. Estrone was detected in all of the samples and 17β-estradiol was detected in one. Concentrations of estrone ranged from between the detection and quantification limits up to 0.63 ng/L. Increases in the concentration of estrone could be observed downstream from potential sources including a drinking water treatment plant. 17β-estradiol was detected below its quantitation limit in a sample taken downstream from a wastewater treatment plant.

Simultaneous detection of endocrine disrupting chemicals including conjugates in municipal wastewater and sludge with enhanced sample pretreatment and UPLC-MS/MS

The co-existence of free and conjugated estrogens and the interference from complex matrices often lead to largely variable detected concentrations and sometimes even negative removal efficiencies of typical endocrine disrupting chemicals (EDCs) in wastewater treatment plants (WWTPs). In this study, a highly selective and sensitive method was developed for simultaneous extraction, elution, and detection of 12 EDCs (i.e., 4 free estrogens, 6 conjugated estrogens, and 2 phenolic compounds) in municipal wastewater and sludge. Sample pretreatment and ultra-performance liquid chromatography-tandem mass spectrometry detection were optimized to improve the detection selectivity and sensitivity. The results indicate that the additional purification process was highly effective in reducing the matrix interference, and the limits of quantification reached as low as 0.04-2.2 ng L(-1) in wastewater and 0.05-4.9 ng g(-1) in sludge for all target EDCs. The developed method was successfully applied to explore the behavior of target EDCs in a local WWTP. The conjugates occupied a considerable portion (4.3-76.9% in molar ratio) of each related estrogen in the influent. Most of the target EDCs could not be completely removed in WWTPs, thus posing a potential threat to aquatic ecosystems.

Impact of wastewater treatment plants on receiving surface waters and a tentative risk evaluation: the case of estrogens and beta blockers

Five estrogenic hormones (unconjugated + conjugated fractions) and 10 beta blockers were analyzed in three wastewater treatment plant (WWTP) effluents and receiving river waters in the area of Lyon, France. In the different samples, only two estrogens were quantified: estrone and estriol. Some beta blockers, such as atenolol, acebutolol, and sotalol, were almost always quantified, but others, e.g., betaxolol, nadolol, and oxprenolol were rarely quantified. Concentrations measured in river waters were in the nanogram per liter range for estrogens and between 0.3 and 210 ng/L for beta blockers depending on the substance and the distance from the WWTP outfall. The impact of the WWTP on the receiving rivers was studied and showed a clear increase in concentrations near the WWTP outfall. For estrogens, the persistence in surface waters was not evaluated given the low concentrations levels (around 1 ng/L). For beta blockers, concentrations measured downstream of the WWTP outfall were up to 16 times higher than those measured upstream. Also, the persistence of metoprolol, nadolol, and propranolol was noted even 2 km downstream of the WWTP outfall. The comparison of beta blocker fingerprints in the samples collected in effluent and in the river also showed the impact of WWTP outfall on surface waters. Finally, a tentative environmental risk evaluation was performed on 15 sites by calculating the ratio of receiving water concentrations to predicted non-effect concentrations (PNEC). For estrogens, a total PNEC of 5 ng/L was considered and these substances were not linked to any potential environmental risk (only one site showed an environmental risk ratio above 1). Unfortunately, few PNECs are available and risk evaluation was only possible for 4 of the 10 beta blockers studied: acebutolol, atenolol, metoprolol, and propranolol. Only propranolol presented a ratio near or above 1, showing a possible environmental risk for 4 receiving waters out of 15.

Analytical methodologies for the determination of endocrine disrupting compounds in biological and environmental samples

Endocrine-disruptor compounds (EDCs) can mimic natural hormones and produce adverse effects in the endocrine functions by interacting with estrogen receptors. EDCs include both natural and synthetic chemicals, such as hormones, personal care products, surfactants, and flame retardants, among others. EDCs are characterised by their ubiquitous presence at trace-level concentrations and their wide diversity. Since the discovery of the adverse effects of these pollutants on wildlife and human health, analytical methods have been developed for their qualitative and quantitative determination. In particular, mass-based analytical methods show excellent sensitivity and precision for their quantification. This paper reviews recently published analytical methodologies for the sample preparation and for the determination of these compounds in different environmental and biological matrices by liquid chromatography coupled with mass spectrometry. The various sample preparation techniques are compared and discussed. In addition, recent developments and advances in this field are presented.

A sensitive liquid chromatography/tandem mass spectrometry method for the determination of natural and synthetic steroid estrogens in seawater and marine biota, with a focus on proposed Water Framework Directive Environmental Quality Standards

RATIONALE

Trace levels of natural and synthetic steroid estrogens estrone (E1), 17β-estradiol (E2) and 17α-ethynyl estradiol (EE2) have been demonstrated to exert adverse effects in exposed organisms. E2 and EE2 have been proposed for inclusion in the Water Framework Directive (WFD) list of priority pollutants; however, the detection and accurate quantification of these compounds provide significant challenges, due to the low detection limits required.

METHODS

A sensitive method combining ultrasonication, solid-phase extraction (SPE) and liquid chromatography/tandem mass spectrometry, with electrospray ionisation in negative mode (LC/ESI-MS/MS), capable of determining E1, E2 and EE2 at concentrations between 0.07 and 60 ng/L for seawater and between 0.4 and 200 ng/g wet weight in Mytilus spp. is reported. Recoveries at the limit of quantification (LOQ) ranged from 95 to 102% and 88 to 100% for water and tissue, respectively. Salinity (12 to 35‰) and typical marine particulate matter loadings (between 10 and 100 mg/L) were not found to affect analyte recoveries.

RESULTS

The first detection of E1 by LC/MS/MS in Irish marine waters (Dublin Bay, at 0.76 ng/L) is reported. Steroids were not detected in Galway Bay, or in any mussel samples from Dublin, Galway and Clare. The level of E2 detected in the dissolved water phase was below the proposed WFD Environmental Quality Standard (EQS) in other surface waters.

CONCLUSIONS

The proposed method is suitable for the detection of E1, E2 and EE2 at biologically relevant concentrations and, due to the specificity offered, is not subject to potential interferences from endogenous E1 and E2 which often complicate the interpretation of estrogenic biomarker assays.

Evaluating the polar organic chemical integrative sampler for the monitoring of beta-blockers and hormones in wastewater treatment plant effluents and receiving surface waters

Wastewater treatment plants (WWTP) are known to be a source of surface water contamination by organic compounds such as pharmaceuticals. The objective of the present work was to study the suitability of the polar organic chemical integrative sampler (POCIS) to monitor beta-blockers and hormones in effluents and surface waters. Four sampling campaigns were carried out in French rivers (the Saône, the Ardières, the Bourbre, and the Seine) between November 2007 and September 2008. Passive samplers were exposed in surface waters, upstream and downstream of WWTP outflows, and in effluents. Exposures lasted for up to 24 d to study the uptake kinetics directly in situ, and repeatability was assessed by exposure of triplicates. A good agreement was found between POCIS and water samples. With the exception of atenolol, beta-blockers showed a linear uptake during at least three weeks, and their sampling rates could be determined in situ. These sampling rates were then used to calculate time-weighted average concentrations of beta-blockers in the Seine River with an overall good accuracy and repeatability. Such calculations could not be performed for hormones because of their variable occurrences and low concentrations in water and POCIS. Polar organic chemical integrative sampler therefore seems to be a suitable tool for monitoring beta-blockers in surface waters impacted by WWTP effluents. Longer exposure durations would be necessary to determine the suitability of POCIS for monitoring hormones. Finally, preliminary assays on the use of several deuterated compounds as performance reference compounds showed promising results for deuterated atenolol.