Couplage de capteurs passifs (POCIS) et de tests de toxicité pour évaluer l'effet des mélanges des pesticides organiques sur des biofilms naturels

National audienceL’utilisation de capteurs passifs, tels que les POCIS (Polar Organic Chemical Integrative Sampler) pour les pesticides organiques les plus hydrophiles, permet une estimation de l’exposition moyenne des biocénoses aux xénobiotiques en milieu aquatique. Ces outils ouvrent donc de nouvelles perspectives pour caractériser les relations entre l’état chimique et l’état biologique et apprécier l’impact écologique des pesticides dans le milieu naturel. Ils présentent également l’avantage de pré-concentrer la contamination de la phase dissoute dans une matrice assez simple, offrant ainsi la possibilité de réaliser des tests de toxicité à partir des substances directement extraites du milieu naturel. Jusqu’alors, les travaux réalisés avec ce type d’approches ont principalement concerné des bioessais sur cultures monospécifiques (ex. cytotoxicité et génotoxicité sur souches bactériennes ou phytotoxicité sur cultures algales). Dans cette étude, les POCIS ont été utilisés comme outils d’échantillonnage intégratif pour évaluer les niveaux de concentration de pesticides organiques dans un petit cours d’eau (Ruiné, Charente) et appréhender leur potentiel toxique sur des biofilms naturels. L’analyse des POCIS collectés dans la zone aval du Ruiné a montré la présence exclusive d’herbicides appartenant aux triazines (atrazine, simazine et terbuthylazine et leurs métabolites) et aux chloroacétamides (métolachlore). Des communautés périphytiques, respectivement prélevées en zone amont et aval du Ruiné, ont été exposées durant 24h et 48h à différentes dilutions réalisées à partir du mélange de pesticides extraits des POCIS. La mesure de la fluorescence chlorophyllienne et de l’activité photosynthétique a permis de mettre en évidence des effets sur les communautés photosynthétiques, avec des réponses variables en fonction de l’origine des biofilms et de leur composition algale. Ces premiers résultats montrent l’intérêt du couplage des échantillonneurs passifs avec des biotests pour apprécier la réponse de biofilms microbiens naturels à des mélanges de toxiques et ouvrent des perspectives intéressantes pour les approches écotoxicologiques en milieu naturel, notamment pour celles de type PICT (Pollution Induced Community Tolerance)

Limitation of flow effect on passive sampling accuracy using POCIS with the PRC approach or o-DGT: A pilot-scale evaluation for pharmaceutical compounds

Flow velocity is known to alter passive sampling accuracy. We investigated the POCIS (Polar Organic Chemical Integrative Sampler) with PRC (Performance Reference Compounds) approach and Diffusive Gradients in Thin Films samplers (o-DGT) to limit the effect of flow on the quantification accuracy of ten model pharmaceuticals compounds (0.16 <= log K-ow <= 4.51). POCIS and o-DGT samplers were exposed for seven days in controlled pilot-scale (hundreds of liters) experiments under quiescent or flowing (2 < V < 18 cm s(-1)) conditions. Under flowing conditions, both POCIS-PRC and o-DGT efficiently limited the flow effect and led, in most cases, to biases within analytical uncertainty (20%). Under quiescent conditions, o-DGT performed accurately (bias <30% for most compounds) whereas the PRC approach was unsuitable to improve upon the accuracy of POCIS (PRC was unable to desorb). Therefore, both approaches are helpful in limiting the effects of flow on accuracy, but only o-DGT is efficient in quiescent conditions. However, o-DGT currently suffers from poorer sensitivity compared to POCIS, but the future development of o-DGT devices with wider windows could overcome this limitation

Improvement of POCIS ability to quantify pesticides in natural water by reducing polyethylene glycol matrix effects from polyethersulfone membranes

International audienceThe presence of polyethylene glycol compounds (PEG) in extracts from polar organic chemical integrative samplers (POCIS) was shown by high resolution time-of-flight mass spectrometry. PEG compounds, which are released by polyethersulfone (PES) membranes used to build POCIS, can induce matrix effects during quantification of performance reference compounds (PRC, DIA-d5) and target pesticides by mass detection, even after chromatographic separation. Dilution of POCIS extracts can reduce this matrix effect, but dilution may induce a decrease in POCIS performance, primarily for quantification limits. To reduce PEG interference during chromatographic analysis, a simple non-damaging washing protocol for PES membranes is proposed. The method consists of 2 successive baths of washing solution (140mL per membrane) of ultrapure water (UPW) and methanol (50/50), stirred at 300 rotations per minute (rpm), followed by a final membrane rinse with UPW (140 mL). The signal from PEG compounds was significantly decreased for washed membranes (between 4 and 6 fold lower). After field deployment, total ion current chromatograms of extracts from POCIS built with washed PES membranes did not display a significant PEG fingerprint. This led to improved quantification accuracy for compounds co-eluting with PEG, i.e. PRC (performance and reference compound, DIA-d5) and some pesticides and metabolites. With washed membranes, an accurate quantification of PRC and pesticides sampled by POCIS was indeed possible without a large extract dilution; 10 times instead of the 25 times needed in unwashed conditions. Assuming that the PRC approach corrects for environmental conditions and sampling rates (R s), a proper PRC (DIA-d5) quantification significantly improved pesticide time weighted average concentration (TWAC) determination in natural water after field deployment

Adaptation of diffusive gradients in thin films technique to sample organic pollutants in the environment: An overview of o-DGT passive samplers

The adaptation of the diffusive gradients in thin films technique (DGT) to sample organic pollutants in the environment, called o-DGT has been performed since 2011 for various types of organic compounds (e.g. pesticides, pharmaceuticals, hormones, endocrine disrupting chemicals, household and personal care products). To sample these different compounds, configuration of the samplers (mainly receiving phase and diffusive gel) has to be adapted. Up-to-date, sampling of 142 organic compounds by this passive sampler have been tested. This review provides the state-of-art of o-DGT passive sampler development, describing theory and modelling, calibration, configuration of the devices, and field applications. The most used configurations were agarose-XAD-18 and agarose-HLB configuration. o-DGT can be used to sample soils and most of natural waters (range of pH 4-9 and ionic strength 0.001-0.1 M).This review discusses current limitation of o-DGT in light of the feedback of DGT use to sample inorganic contaminants. It mainly concern the low sampling rates currently obtained by o-DGT compared to other passive samplers. This weakness could be compensated in the future with new sampler's design allowing an increase in exposure area

Passive sampling of anionic pesticides using the Diffusive Gradients in Thin films technique (DGT)

International audienceDGT passive samplers using Oasis® HLB or Oasis® MAX sorbent were developed for anionic pesticides sampling. They were tested using four model compounds (i.e. bentazon, chlorsulfuron, ioxynil and mecoprop). Polyacrylamide diffusive gel was found to be more suitable than agarose gel for most anionic pesticides sampling. An elution procedure was optimized and diffusion coefficients were determined for quantitative use of the samplers. Depending on the DGT configuration used (HLB or MAX), accuracies better than 30% were demonstrated in laboratory for pH from 3 to 8 and ionic strengths from 10−2 to 1 M. Combined with the effective binding capacities of samplers (≥9 μg for each pesticide) and limits of quantification of the method (≤13 ng.L−1 using Q-TOF detector) monitoring of numerous aquatic systems can be expected. Except for ioxynil, accurate quantifications were demonstrated in laboratory using a spiked natural water for HLB-DGT whereas MAX-DGT did not give satisfactory results. A further in situ validation was performed in two rivers and showed identical detection frequency between HLB-DGT and POCIS of anionic pesticides (bentazon and mesotrione) whereas calculated concentrations, although within the same order of magnitude, could differ (<70%). HLB-DGT could therefore constitute an interesting alternative to other passive samplers for the monitoring of several anionic pesticides in aquatic systems but more work is required for quantification of molecules from hydroxybenzonitrile chemical group (ioxynil)

Development of a multi-hormone analysis method by LC-MS/MS for environmental water application using diffusive gradient in thin films

International audienceAn analysis method for four families of hormones (estrogens, progestins, androgens and prostaglandins), dedicated to an efficient water monitoring with passive sampling, was developed using a liquid chromatography tandem mass spectrometry with triple quadrupole coupling and universal electrospray ionisation. Thirteen natural and synthetic hormones in ultra-pure water could be analysed in a single run according to the French Standard NF T90-210: calibration range of 0.1 (except for 17 beta-Estradiol, Estriol, Estrone and Diethylstilbestrol, from 0.5 mu g/L; and Ethinylestradiol, from 1 mu g/L) to 20 mu g/L with linear regressions (R2 >= 0.96), maximum accuracy deviations of 30% at intermediate fidelity for three concentration references (1, 10 and 20 mu g/L) and instrumental LOQs from 0.05 to 1 mu g/L. The stability of 11 hormones (10 mu g/L) was studied under several storage conditions and sample evaporation. All selected hormones were stable for 60 days at -18 degrees C, 7 days at 4 degrees C and 7 days at 20 degrees C but continued drying flow after evaporation should be avoided, especially for 17 alpha-Estradiol, Estrone and Diethylstilbestrol. Observed matrix effects using o-DGT extracts (diffusive gradient in thin-film sampler for polar organics) containing an environmental matrix varied from 24 to 92% but all matrix effects were corrected with IS use. Therefore, the developed method, coupled with o-DGT, was tested with the o-DGT deployment in rivers. Using diffusion coefficients from the literature or lab determined, the concentrations in the rivers varied for Estrone from 1.8 ng/L to 2.5 ng/L, and for Androstenedione from 0.4 to 1.1 ng/L

Combining polar organic chemical integrative sampler (POCIS) with toxicity testing to evaluate pesticide mixture effects on natural phototrophic biofilms

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

International audienceThe 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)

Proposal of a new empirical model with flow velocity to improve time-weighted average concentration estimates from the Polar Organic Chemical Integrative Samplers

International audienceIt is now widely recognized that the sampling rate of Polar Organic Chemical Integrative Samplers (POCIS) is significantly affected by flow velocity, which can cause a consequent bias when determining time-weighted average concentrations (TWAC). We already observed the desorption of deisopropylatrazine (DIA) over time when added to the receiving phase of a POCIS. This desorption rate was particularly influenced by flow velocity, in an agitated water environment in situ. In the method presented here, we calibrated 30 pesticides under controlled laboratory conditions, varying the flow velocity over four levels. We simultaneously studied the desorption rate of DIA-d5 (a deuterated form of DIA) over time. An empirical model based on a power law involving flow velocity was used to process the information from the accumulation kinetics of the compounds of interest and elimination of DIA-d5. This type of model makes it possible to consider the effect of this crucial factor on exchange kinetics, and then to obtain more accurate TWACs with reduced bias and more acceptable dispersion of results