Determination of the uptake and release rates of multifamilies of endocrine disruptor compounds on the polar C18 Chemcatcher. Three potential performance reference compounds to monitor polar pollutants in surface water by integrative sampling

A year-long passive sampling of phenolic endocrine disrupting chemicals in the East River, South China

The occurrence of endocrine disrupting chemicals (EDCs) in the aquatic environment is a global concern. In this study, we employed two different passive samplers Diffusive Gradients in Thin-films (DGT) and Chemcatcher for in situ measurement of 8 phenolic EDCs in the East River of the Pearl River system over one-year. These data were assessed alongside results from traditional grab sampling. Six chemicals (4tOP, 4NP, BPA, E1, EE2 and DES) were regularly detected in the water samples, of which the three phenols (i.e. 4tOP, 4NP and BPA) were in all samples and at high concentrations (0.4-1040 ng/L for 4tOP, 2.6-58500 ng/L for NP and 11.4-123300 ng/L for BPA). Fewer target chemicals were detected in both passive samplers, with only 4tOP, 4NP and BPA found in most samplers; E1 and DES were occasionally measurable above detection limits. The higher (by about a factor of 2-3) measurements provided by DGT compared to Chemcatcher could be attributed to the effect of the diffusive boundary layer on Chemcatcher uptake or the strong adsorption of target chemicals on the Chemcatcher PES filter. The temporal trends of EDC monthly loadings indicated that they were from different sources and that WWTPs were not effective in EDC removal and/or there was still some untreated wastewater discharged into the rivers.

Development of a Passive Sampling Technique for Measuring Pesticides in Waters and Soils

It is essential to monitor pesticides in the environment to help ensure water and soil quality. The diffusive gradients in thin-films (DGT) technique can measure quantitative in situ labile (available) concentrations of chemicals in water, soil, and sediments. This study describes the systematic development of the DGT technique for nine current pesticides, selected to be representative of different classes with a wide range of properties, with two types of resins (HLB (hydrophilic-lipophilic-balanced) and XAD 18) as binding layer materials. The masses of pesticides accumulated by DGT devices were proportional to the deployment time and in inverse proportion to the thickness of the diffusive layer, in line with DGT theoretical predictions. DGT with both resin gels were tested in the laboratory for the effects of typical environmental factors on the DGT measurements. DGT performance was independent of the following: pH in the range of 4.7-8.2; dissolved organic matter concentrations <20 mg L^-1; and ionic strength from 0.01 to 0.25 M, although it was slightly affected at 0.5 M in some cases. This confirms DGT as a sampler suitable for controlled studies of environmental processes affecting pesticides. Field applications of DGT to measure pesticides in situ in waters and controlled laboratory measurements on five different soils (prepared at fixed soil/water ratios) demonstrated DGT is a suitable tool for environmental monitoring in waters and for investigating chemical processes in soils.

Review of atrazine sampling by polar organic chemical integrative samplers and Chemcatcher

A key success factor for the performance of passive samplers is the proper calibration of sampling rates. Sampling rates for a wide range of polar organic compounds are available for Chemcatchers and polar organic chemical integrative samplers (POCIS), but the mechanistic models that are needed to understand the effects of exposure conditions on sampling rates need improvement. Literature data on atrazine sampling rates by these samplers were reviewed with the aim of assessing what can be learned from literature reports of this well-studied compound and identifying knowledge gaps related to the effects of flow and temperature. The flow dependency of sampling rates could be described by a mass transfer resistance model with 1 (POCIS) or 2 (Chemcatcher) adjustable parameters. Literature data were insufficient to evaluate the temperature effect on the sampling rates. An evaluation of reported sampler configurations showed that standardization of sampler design can be improved: for POCIS with respect to surface area and sorbent mass, and for Chemcatcher with respect to housing design. Several reports on atrazine sampling could not be used because the experimental setups were insufficiently described with respect to flow conditions. Recommendations are made for standardization of sampler layout and documentation of flow conditions in calibration studies. Environ Toxicol Chem 2018;37:1786-1798. © 2018 SETAC.

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.

Monitoring Herbicide Concentrations and Loads during a Flood Event: A Comparison of Grab Sampling with Passive Sampling

The suitability of passive samplers (Chemcatcher) as an alternative to grab sampling in estimating time-weighted average (TWA) concentrations and total loads of herbicides was assessed. Grab sampling complemented deployments of passive samplers in a tropical waterway in Queensland, Australia, before, during and after a flood event. Good agreement was observed between the two sampling modes in estimating TWA concentrations that was independent of herbicide concentrations ranging over 2 orders of magnitude. In a flood-specific deployment, passive sampler TWA concentrations underestimated mean grab sampler (n = 258) derived concentrations of atrazine, diuron, ametryn, and metolachlor by an average factor of 1.29. No clear trends were evident in the ratios of load estimates from passive samplers relative to grab samples that ranged between 0.3 and 1.8 for these analytes because of the limitations of using TWA concentrations to derive flow-weighted loads. Stratification of deployments by flow however generally resulted in noticeable improvements in passive sampler load estimates. By considering the magnitude of the uncertainty (interquartile range and the root-mean-squared error) of load estimates a modeling exercise showed that passive samplers were a viable alternative to grab sampling since between 3 and 17 grab samples were needed before grab sampling results had less uncertainty.

Improving Toxicity Assessment of Pesticide Mixtures: The Use of Polar Passive Sampling Devices Extracts in Microalgae Toxicity Tests

Complexity of contaminants exposure needs to be taking in account for an appropriate evaluation of risks related to mixtures of pesticides released in the ecosystems. Toxicity assessment of such mixtures can be made through a variety of toxicity tests reflecting different level of biological complexity. This paper reviews the recent developments of passive sampling techniques for polar compounds, especially Polar Organic Chemical Integrative Samplers (POCIS) and Chemcatcher® and the principal assessment techniques using microalgae in laboratory experiments. The progresses permitted by the coupled use of such passive samplers and ecotoxicology testing as well as their limitations are presented. Case studies combining passive sampling devices (PSD) extracts and toxicity assessment toward microorganisms at different biological scales from single organisms to communities level are presented. These case studies, respectively, aimed (i) at characterizing the "toxic potential" of waters using dose-response curves, and (ii) at performing microcosm experiments with increased environmental realism in the toxicant exposure in term of cocktail composition and concentration. Finally perspectives and limitations of such approaches for future applications in the area of environmental risk assessment are discussed.

Molecularly Imprinted Dispersive Solid-Phase Extraction for the Determination of Triazine Herbicides in Grape Seeds by High-Performance Liquid Chromatography

Molecular imprinting technique, regarded as one of the current state-of-the-art researches, was incorporated with the simple dispersive solid-phase extraction (MI-DSPE) in this work for the extraction of triazine herbicides in grape seeds. The atrazine molecularly imprinted polymers (MIPs) were successfully prepared and characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The imprinting particles were used as the adsorbent in DSPE. Thus, a simple, rapid and selective method based on MIPs coupled with DSPE was established for the simultaneous cleaning-up and quantitative extraction of four triazine herbicides in grape seeds. The experiment parameters, including type of washing solvents, washing time and type of eluting solvents, were investigated and optimized. The performance of the present method was validated by high-performance liquid chromatography. Good linear responses were obtained in concentration range of 0.010-5.0 µg g(-1)with correlation coefficients (r(2)) higher than 0.9993. The recoveries at two spiked levels (1.0 and 2.0 µg g(-1)) were between 81.2 and 113.0% with relative deviations ranging from 1.2 to 10.7%. The limits of detection were ranged between 0.006 and 0.013 µg g(-1), which were lower than the values required by European regulations.

Overview of the Chemcatcher® for the passive sampling of various pollutants in aquatic environments Part A: Principles, calibration, preparation and analysis of the sampler

The passive sampler Chemcatcher(®), which was developed in 2000, can be adapted for various types of water contaminants (e.g., trace metals, polycyclic aromatic hydrocarbons, pesticides and pharmaceutical residues) depending on the materials chosen for the receiving phase and the membrane. The Chemcatcher(®) has been used in numerous research articles in both laboratory experiments and field exposures, and here we review the state-of-the-art in applying this passive sampler. Part A of this review covers (1) the theory upon which the sampler is based (i.e., brief theory, calculation of water concentration, Performance and Reference Compounds), (2) the preparation of the device (i.e., sampler design, choice of the membrane and disk, mounting of the tool), and (3) calibration procedures (i.e., design of the calibration tank, tested parameters, sampling rates).

Study of different Chemcatcher configurations in the monitoring of nonylphenol ethoxylates and nonylphenol in aquatic environment

The main aim of the European Union Water Framework Directive (WFD) (2000/60/EC) is to protect rivers, lakes, coastal waters and groundwaters (EC 2000). The implementation of the WFD requires monitoring the concentration levels of several priority pollutants such as nonylphenol ethoxylates (NPEOs) and nonylphenol (NP) in the area of EU. The present practices for determining the concentration levels of various pollutants are, in many respects, insufficient, and there is an urgent need to develop more cost-effective sampling methods. A passive sampling tool named Chemcatcher was tested for monitoring NPEOs and NP in aqueous media. These environmentally harmful substances have been widely used in different household and industrial applications, and they affect aquatic ecosystems, for example, by acting as endocrine disrupting compounds. The suitability of different receiving phases which were sulfonated styrene-divinylbenzene reversed phase polymer (SDB-RPS), standard styrene-divinyl benzene polymer (SDB-XC) and C-18 (octadecyl) was assessed in laboratory and field trials. The effect of a diffusion membrane on the accumulation of studied compounds was also investigated. The SDB-XC and C-18 receiving phases collected the NPEOs and NP most effectively. The water flow affected the accumulation factor of the studied substances in the field trials, and the water concentrations calculated using sampling rates were tenfold lower than those measured with conventional spot sampling. The concentration of the analytes in spot samples taken from the sampling sites might be higher because in that case, the particle-bound fraction is also measured. The NPEOs readily attach to suspended matter, and therefore, the total concentration of such compounds in water is much higher. Also, the spot samples were not taken daily but once a week, while the passive samplers collected the compounds continuously for 2- or 4-week time periods. This may cause differences when comparing the results of those two methods as well. Both techniques can be applied for monitoring the concentration levels at different sampling sites, but the calculated and measured analyte concentrations in surrounding water are not necessarily comparable with each other. More experiments are still needed to study the effect of hydrological issues and humic substances on the accumulation of chemicals. However, the Chemcatcher passive sampler gives valuable information about the mean concentration levels of studied compounds during 2- or 4-week sampling period. This is important for comparison of annual monitoring results, especially in sampling sites with rapidly fluctuating concentrations.

Optimization of the polar organic chemical integrative sampler for the sampling of acidic and polar herbicides

This paper presents an optimization of the pharmaceutical Polar Organic Chemical Integrative Sampler (POCIS-200) under controlled laboratory conditions for the sampling of acidic (2,4-dichlorophenoxyacetic acid (2,4-D), acetochlor ethanesulfonic acid (ESA), acetochlor oxanilic acid, bentazon, dicamba, mesotrione, and metsulfuron) and polar (atrazine, diuron, and desisopropylatrazine) herbicides in water. Indeed, the conventional configuration of the POCIS-200 (46 cm(2) exposure window, 200 mg of Oasis® hydrophilic lipophilic balance (HLB) receiving phase) is not appropriate for the sampling of very polar and acidic compounds because they rapidly reach a thermodynamic equilibrium with the Oasis HLB receiving phase. Thus, we investigated several ways to extend the initial linear accumulation. On the one hand, increasing the mass of sorbent to 600 mg resulted in sampling rates (R s s) twice as high as those observed with 200 mg (e.g., 287 vs. 157 mL day(-1) for acetochlor ESA). Although detection limits could thereby be reduced, most acidic analytes followed a biphasic uptake, proscribing the use of the conventional first-order model and preventing us from estimating time-weighted average concentrations. On the other hand, reducing the exposure window (3.1 vs. 46 cm(2)) allowed linear accumulations of all analytes over 35 days, but R s s were dramatically reduced (e.g., 157 vs. 11 mL day(-1) for acetochlor ESA). Otherwise, the observation of biphasic releases of performance reference compounds (PRC), though mirroring acidic herbicide biphasic uptake, might complicate the implementation of the PRC approach to correct for environmental exposure conditions.

Uptake and release kinetics of 22 polar organic chemicals in the Chemcatcher passive sampler

The Chemcatcher passive sampler, which uses Empore™ disks as sampling phase, is frequently used to monitor polar organic chemicals in river water and effluents. Uptake kinetics need to be quantified to calculate time-weighted average concentrations from Chemcatcher field deployments. Information on release kinetics is needed if performance reference compounds (PRCs) are used to quantify the influence of environmental conditions on the uptake. In a series of uptake and elimination experiments, we used Empore™ SDB disks (poly(styrenedivinylbenzene) copolymer modified with sulfonic acid groups) as a sampling phase and 22 compounds with a logK(ow) (octanol-water partitioning coefficient) range from -2.6 to 3.8. Uptake experiments were conducted in river water or tap water and lasted up to 25 days. Only 1 of 22 compounds (sulfamethoxazole) approached equilibrium in the uptake trials. Other compounds showed continuing non-linear uptake, even after 25 days. All compounds could be released from SDB disks, and desorption was proportionally higher in disks loaded for shorter periods. Desorption showed two-phase characteristics, and desorption was proportionally higher for passively sorbed compounds compared to actively loaded compounds (active loading was performed by pulling spiked river water over SDB disks using vacuum). We hypothesise that the two-phase kinetics and better retention of actively loaded compounds--and compounds loaded for a longer period--may be caused by slow diffusion of chemicals within the polymer. As sorption and desorption did not show isotropic kinetics, it is not possible to develop robust PRCs for adsorbent material like SDB disks.

Use of mixed-mode ion exchange sorbent for the passive sampling of organic acids by polar organic chemical integrative sampler (POCIS)

Acidic herbicides are increasingly monitored in freshwater, since their high solubility favors their rapid transfer to the water phase. Therefore, contaminant levels in the water can vary rapidly and passive sampling would be preferred over spot sampling to integrate all pollution events over a given exposure time. In this work, we propose to compare the conventional pharmaceutical polar organic chemical integrative sampler (POCIS) with modified POCISs containing two different receiving phases: a standard polystyrene divinylbenzene polymer with a higher specific surface area (Chromabond HR-X) and a mixed-mode anion exchange sorbent providing additional strong anion exchange interaction sites (Oasis MAX). Due to its hydrophobic character, Chromabond HR-X had little interaction with water (no sampling of acidic herbicides); whereas Oasis MAX provided acceptable sampling parameters (longer kinetic regime together with higher sampling rates). Additional experiments with POCIS-MAX showed no influence of nitrates on analyte uptakes, and linear isotherms reaching 10 μg L⁻¹, supporting the applicability of this device for the sampling of organic acids in continental water. The performance and reference compound (PRC) approach would be then applicable for POCIS-MAX if no competition is observed with other anions, especially organic acids (e.g., humic acids).