Patrick Mazellier

Evaluation of the Use of Performance Reference Compounds in an Oasis-HLB Adsorbent Based Passive Sampler for Improving Water Concentration Estimates of Polar Herbicides in Freshwater

Passive samplers such as the Polar Organic Chemical Integrative Sampler (POCIS) are useful tools for monitoring trace levels of polar organic chemicals in aquatic environments. The use of performance reference compounds (PRC) spiked into the POCIS adsorbent for in situ calibration may improve the semiquantitative nature of water concentration estimates based on this type of sampler. In this work, deuterium labeled atrazine-desisopropyl (DIA-d5) was chosen as PRC because of its relatively high fugacity from Oasis HLB (the POCIS adsorbent used) and our earlier evidence of its isotropic exchange. In situ calibration of POCIS spiked with DIA-d5 was performed, and the resulting time-weighted average concentration estimates were compared with similar values from an automatic sampler equipped with Oasis HLB cartridges. Before PRC correction, water concentration estimates based on POCIS data sampling rates from a laboratory calibration exposure were systematically lower than the reference concentrations obtained with the automatic sampler. Use of the DIA-d5 PRC data to correct POCIS sampling rates narrowed differences between corresponding values derived from the two methods. Application of PRCs for in situ calibration seems promising for improving POCIS-derived concentration estimates of polar pesticides. However, careful attention must be paid to the minimization of matrix effects when the quantification is performed by HPLC-ESI-MS/MS.

Liquid chromatography coupled with tandem mass spectrometry method for thirty-three pesticides in natural water and comparison of performance between classical solid phase extraction and passive sampling approaches.

The aim of this study is to propose an analytical method for determining different classes of pesticides in water using LC-ESI-MS/MS. Two techniques of field-sampling and analyte extraction were used: solid phase extraction (SPE) of water samples from active sampling and field exposure of Polar Organic Chemical Integrative Samplers (POCIS). We have worked with thirty-three molecules representing eight pesticide classes: carbamates, chloroacetanilides, dicarboximides, morpholines, organophosphorous, phenylureas, strobilurines and triazines. First, liquid chromatography separation protocols and the optimization of the ESI-MS/MS parameters were developed. Then, the SPE step was optimized to obtain acceptable levels of recovery for the various classes of molecules. The matrix effect that may significantly lower the ionization efficiency with ESI interfaces was evaluated and minimized. The performances (limits of quantification, accuracy and precision) of the SPE and POCIS techniques were evaluated, and a comparison between the active and passive sampling techniques was carried out with a field application.

Photodegradation of the steroid hormones 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) in dilute aqueous solution

The photochemical transformation of natural estrogenic steroid 17beta-estradiol (E2) and the synthetic oral contraceptive 17alpha-ethinylestradiol (EE2) has been studied in dilute non buffered aqueous solution (pH 5.5-6.0) upon monochromatic (254 nm) and polychromatic (lambda>290 nm) irradiation. Upon irradiation at 254 nm, the quantum yields of E2 and EE2 photolysis were similar and evaluated to be 0.067+/-0.007 and 0.062+/-0.007, respectively. Upon polychromatic excitation, and by using phenol as chemical actinometer, the photolysis efficiencies have been determined to be 0.07+/-0.01 and 0.08+/-0.01 for E2 and EE2, respectively. For both estrogens, photodegradation by-products were identified with GC/MS and LC/MS. In a first step, a model compound--5,6,7,8-tetrahydro-2-naphthol (THN)--, which represents the photoactive phenolic group, was used to obtain basic photoproduct structural informations. Numerous primary and secondary products were observed, corresponding to hydroxylated phenolic- or quinone-type compounds.

Phototransformation of ibuprofen and ketoprofen in aqueous solutions.

The UV (254 nm) and UV/VUV (254/185 nm) photolysis of two anti-inflammatory drugs, ibuprofen and ketoprofen, have been studied in aqueous solutions as a possible process for the removal of non-biodegradable compounds. We have examined the effects of dissolved oxygen and initial target concentration. Upon irradiation at 254 nm, the decomposition rate of ketoprofen is almost forty times higher as it of ibuprofen whilst VUV irradiation only increased the ibuprofen decomposition rate. The presence of dissolved oxygen accelerated the photodegradation of ibuprofen, whereas no effect was observed on the degradation of ketoprofen. The maximum quantum yield for the phototransformation was 0.2. The rate of mineralization in both cases was ∼60%, even after 1h of treatment and this suggests the formation of stable by-products which were identified using GC-MS and HPLC-MS, respectively.

Photodegradation of estrone enhanced by dissolved organic matter under simulated sunlight

In the present work the degradation of estrone (E1) a natural estrogenic hormone has been studied under simulated solar irradiation. The photodegradation of E1 has been investigated in the absence and in the presence of 7.7-8.9 mg L(-1) of dissolved organic carbon (DOC), under solar light simulation with irradiance approximating that of the sun. DOC extracts from different origins have been used. Half-lives ranging between 3.9 h and 7.9 h were observed. Results indicated that E1 was photodegraded even in the absence of DOC. The presence of DOC was found to enhance the degradation of E1. Experiments performed with the addition of reactive species scavengers (azide ions and 2-propanol) have shown that these two species play a significant role in the photodegradation. Some experiments have been performed with a DOC previously submitted to solar irradiation. Changes in optical and physico-chemical properties of DOC strongly affect its photoinductive properties, and hence its efficiency on E1 degradation. A part of the study consisted in the investigation of photoproducts structures. Five photoproducts were shown by chromatographic analysis: one arising from direct photolysis and the four others from DOC photoinduced degradation.

Transformation of carbendazim induced by the H2O2/UV system in the presence of hydrogenocarbonate ions : involvement of the carbonate radical

The transformation of the fungicide carbendazim by hydroxyl radicals generated by the photolysis (λexc.u2006=u2006254 nm) of hydrogen peroxide in aqueous solution has been studied in the absence and in the presence of hydrogenocarbonate ions. In the presence of high concentrations of hydrogen peroxide, the second-order rate constant of the reaction of HO˙ radicals with carbendazim has been determined to be equal to (2.2u2006±u20060.3)u2006×u2006109 L.mol−1.s−1. The identification of the main degradation by-products shows the existence of two different reaction sites for carbendazim induced degradation: the benzene ring and the methyl group. Good simulations of carbendazim disappearance have been obtained by kinetic modelling over a wide range of initial H2O2 concentrations. In the presence of hydrogenocarbonate ions, a quenching effect is observed and the simulations lead to an underestimation of the carbendazim disappearance. This is because of the involvement of the carbonate radicals, which react with carbendazim with a second-order rate constant evaluated to be equal to (6u2006±u20062)u2006×u2006106 L.mol−1.s−1 by kinetic modelling. When the starting concentration of HCO3− is high enough, the elimination of carbendazim by CO3˙ becomes the major route of carbendazim transformation.

Degradation of naproxen by UV, VUV photolysis and their combination

Naproxen is a widely used nonsteroidal anti-inflammatory drug. Recently, this medicine was detected both in natural waters (up to 1.5 μg L(-1)) and in sewage treatment plant effluents (up to 5.2 μg L(-1)). Moreover, naproxen is only partly eliminated by classical processes used in sewage treatment plants. Therefore, its degradation is of utmost interest. Advanced oxidation processes proved to be the most suitable methods for the elimination of persistent organic contaminants. In this work ultraviolet (UV, 254 nm), vacuum ultraviolet photolysis (VUV, 172 nm) and their combination (UV/VUV, 254/185 nm) were investigated. The efficiency of the methods increased in the following order: UV < VUV < UV/VUV photolysis. However, VUV irradiation was found to mineralize the contaminant molecule most effectively. The chemical structures of three out of four aromatic by-products and of some aliphatic carboxylic acids were presumed. The effects of dissolved O2 and the initial concentration of naproxen on the degradation were also investigated.

Photochemical behavior of the fungicide carbendazim in dilute aqueous solution

Abstract The direct phototransformation of the fungicide carbendazim has been studied upon monochromatic irradiation at 254xa0nm. In aqueous solution, carbendazim presents the properties of weak base. The p K a of carbendazim has been determined equal to 4.53±0.07 (by UV-Vis spectrophotometric measurements). Both forms of carbendazim present an emission of fluorescence. The wavelength for the maximum of emission are 393 and 305xa0nm for the protonated and the neutral form respectively. The fluorescence quantum yields have been measured and values equal to 5×10 −3 and 9×10 −3 have, respectively been obtained for the NH + and N form ( λ exc =254xa0nm). Upon irradiation at 254xa0nm, the quantum yield of carbendazim phototransformation has been determined. It is respectively equal to 2.9×10 −3 and 2.3×10 −3 for the protonated and the neutral form. The increase of oxygen concentration leads to an increase of the phototransformation rate at pH 8.4. On the contrary, the addition of bicarbonate ions inhibits the phototransformation process. This inhibition is consistent with a hypothesis of a Stern–Volmer quenching. The Stern–Volmer quenching constant has been evaluated to 400xa0M −1 . Degradation products have been identified by liquid chromatography coupled with mass spectrometry. The major one was aminobenzimidazole and its formation could be explained by a photohydrolysis mechanism.

Quantitative on-line preconcentration-liquid chromatography coupled with tandem mass spectrometry method for the determination of pharmaceutical compounds in water

One of the current environmental issues concerns the presence and fate of pharmaceuticals in water bodies as these compounds may represent a potential environmental problem. The characterization of pharmaceutical contamination requires powerful analytical method able to quantify these pollutants at very low concentration (few ng L(-1)). In this work, a multi-residue analytical methodology (on-line solid phase extraction-liquid chromatography-triple quadrupole mass spectrometry using positive and negative electrospray ionization) has been developed and validated for 40 multi-class pharmaceuticals and metabolites for tap and surface waters. This on-line SPE method was very convenient and efficient compared to classical off-line SPE method because of its shorter total run time including sample preparation and smaller sample volume (1 mL vs up to 1 L). The optimized method included several therapeutic classes as lipid regulators, antibiotics, beta-blockers, non-steroidal anti-inflammatories, antineoplastic, etc., with various physicochemical properties. Quantification has been achieved with the internal standards. The limits of detection are between 0.7 and 15 ng L(-1) for drinking waters and 2-15 ng L(-1) for surface waters. The inter-day precision values are below 20% for each studied level. The improvement and strength of the analytical method has been verified along a monitoring of these 40 pharmaceuticals in Isle River, a French stream located in the South West of France. During this survey, 16 pharmaceutical compounds have been detected.

Transformation of 4-tert-octylphenol by UV irradiation and by an H2O2/UV process in aqueous solution

The transformation of the organic pollutant 4-(1,1,3,3-tetramethylbutyl)phenol (4-tert-octylphenol; OP) upon irradiation at 253.7 nm and by hydroxyl radicals generated by the photolysis (lambda(exc) = 253.7 nm) of hydrogen peroxide in aqueous solution has been studied. The quantum yield of direct OP photolysis in pure aqueous solution was evaluated to be 0.058 +/- 0.004 in aerated conditions ([O2] = 272 microM). The rate of photoreaction depends on oxygen concentration; it increases with increasing [O2]. 4-tert-Octylcatechol has been identified as one of the degradation products, together with a dimeric structure. The probable mechanism of OP photolysis involves photoejection of an electron from the singlet state, leading to the formation of the 4-tert-octylphenoxyl radical. In the presence of hydrogen peroxide, the degradation of octylphenol by hydroxyl radicals has been observed. The second-order rate constant was found to be (6.4 +/- 0.5) x 10(9) M(-1) s(-1) by direct measurement at various high concentrations of hydrogen peroxide and competitive kinetic measurements using atrazine as the competitor. The degradation products are 4-tert-octylcatechol, again, and 2-hydroxy-5-tert-octylbenzoquinone. The later product may arise from the oxidation of 4-tert-octylcatechol by hydrogen peroxide or from a subsequent reaction of hydroxyl radicals with 4-tert-octylcatechol. Kinetic modelling when using either purified water or natural water successfully simulated the elimination of 4-tert-octylphenol by UV and H2O2/UV processes.