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International audience; These last decades, it has been widely assumed that 18-crown-6-ether (CE) plays a spectator role during the chemical processes occurring in isolated host-guest complexes between peptides or proteins and CE, after activation in mass spectrometers. Our present experimental and theoretical results challenge this hypothesis by showing that CE can abstract a proton or a protonated molecule from protonated peptides after activation by collisions in argon or electron capture/transfer. Furthermore, thanks to comparison between experimental and calculated values of collision cross-sections, we demonstrate that CE can change binding site after electron transfer. We also propose detailed mechanisms for these processes.

Ion signal detection at the true (unperturbed) cyclotron frequency instead of the conventional reduced cyclotron frequency has remained a formidable challenge since the inception of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Recently, routine FT-ICR MS at the true cyclotron frequency has become a reality with the implementation of ICR cells with narrow aperture detection electrodes (NADEL). Here, we describe the development and implementation of the next generation of these cells, namely, a 2xNADEL ICR cell, which comprises four flat detect and four ∼45° cylindrical excite electrodes, enabling independent ion excitation and quadrupolar ion detection. The performance of the 2xNADEL ICR cell was evaluated on two commercial FT-ICR MS platforms, 10 T LTQ FT from Thermo Scientific and 9.4 T SolariX XR from Bruker Daltonics. The cells provided accurate mass measurements in the analyses of singly and multiply charged peptides (root-mean-square, RMS, mass error Δm/m of 90 ppb), proteins (Δm/m = 200 ppb), and petroleum fractions (Δm/m < 200 ppb). Due to the reduced influence of measured frequency on the space charge and external (trapping) electric fields, the 2xNADEL ICR cells exhibited stable performance in a wide range of trapping potentials (1-20 V). Similarly, in a 13 h rat brain MALDI imaging experiment, the RMS mass error did not exceed 600 ppb even for low signal-to-noise ratio analyte peaks. Notably, the same set of calibration constants was applicable to Fourier spectra in all pixels, reducing the need for recalibration at the individual pixel level. Overall, these results support further experimental development and fundamentals investigation of this promising technology.

International audience; FT-ICR MS (Fourier-transform ion cyclotron resonance mass spectrometry) analysis has shown great potential to aid in the understanding of the extremely high molecular diversity of cloud water samples. The main goal of this work was to determine the differences in terms of formula assignment for analytical (i.e., measurement replicates) and experimental replicates of a given cloud water sample. The experimental replicates, obtained by solid phase extraction, were also compared to the results obtained for freeze-dried samples to evaluate whether the presence of salts interferes with the analysis. Two S/N ratios, generally adopted for atmospheric samples, were evaluated, and three different algorithms were used for assignment: DataAnalysis 5.3 (Bruker), Composer (Sierra Analytics), and MFAssignR (Chemical Advanced Resolution Methods Lab). In contrast to other works, we wanted to treat this comparison from the point of view of users, who usually must deal with a simple list of m/z ratios and intensity with limited access to the mass spectrum characteristics. The aim of this study was to establish a methodology for the treatment of atmospheric aqueous samples in light of the comparison of three different software programs, to enhance the possibility of data comparison within samples.

Sclareol, an antifungal specialized metabolite produced by clary sage, Salvia sclarea, is the starting plant natural molecule used for the hemisynthesis of the perfume ingredient ambroxide. Sclareol is mainly produced in clary sage flower calyces; however, the cellular localization of the sclareol biosynthesis remains unknown. To elucidate the site of sclareol biosynthesis, we analyzed its spatial distribution in the clary sage calyx epidermis using laser desorption/ionization mass spectrometry imaging (LDI–FTICR-MSI) and investigated the expression profile of sclareol biosynthesis genes in isolated glandular trichomes (GTs). We showed that sclareol specifically accumulates in GTs’ gland cells in which sclareol biosynthesis genes are strongly expressed. We next isolated a glabrous beardless mutant and demonstrate that more than 90% of the sclareol is produced by the large capitate GTs. Feeding experiments, using 1-13C-glucose, and specific enzyme inhibitors further revealed that the methylerythritol-phosphate (MEP) biosynthetic pathway is the main source of isopentenyl diphosphate (IPP) precursor used for the biosynthesis of sclareol. Our findings demonstrate that sclareol is an MEP-derived diterpene produced by large capitate GTs in clary sage emphasing the role of GTs as biofactories dedicated to the production of specialized metabolites.

Rationale High-resolution mass spectrometry based non-targeted screening has a huge potential for applications in environmental sciences, engineering and regulation. However, it produces large datasets for which full appropriate processing is a real challenge; the development of processing software is the last building-block to enable large-scale use of this approach. Methods A new software application, SPIX, has been developed to extract relevant information from high-resolution mass spectral datasets. Dealing with intrinsic sample variability and reducing operator subjectivity, it opens up opportunities and promising prospects in many areas of analytical chemistry. SPIX is freely available at: http://spix.webpopix.org. Results Two features of the software are presented in the field of environmental analysis. An example illustrates how SPIX reveals photodegradation reactions in wastewater by fitting kinetic models to significant changes in ion abundance over time. A second example shows the ability of SPIX to detect photoproducts at trace amounts in river water, through comparison of datasets from samples taken before and after irradiation. Conclusions SPIX has shown its ability to reveal relevant modifications between two series of large datasets, allowing, for instance, the study of the consequences of a given event on a complex substrate. Most of all - and it is to our knowledge the only software currently available allowing this - it can reveal and monitor any kind of reaction in all types of mixture.

Ion cyclotron resonance (ICR) cells provide stability and coherence of ion oscillations in crossed electric and magnetic fields over extended periods of time. Using the Fourier transform enables precise measurements of ion oscillation frequencies. These precisely measured frequencies are converted into highly accurate mass-to-charge ratios of the analyte ions by calibration procedures. In terms of resolution and mass accuracy, Fourier transform ICR mass spectrometry (FT-ICR MS) offers the highest performance of any MS technology. This is reflected in its wide range of applications. However, in the most challenging MS application, for example, imaging, enhancements in the mass accuracy of fluctuating ion fluxes are required to continue advancing the field. One approach is to shift the ion signal power into the peak corresponding to the true cyclotron frequency instead of the reduced cyclotron frequency peak. The benefits of measuring the true cyclotron frequency include increased tolerance to electric fields within the ICR cell, which enhances frequency measurement precision. As a result, many attempts to implement this mode of FT-ICR MS operation have occurred. Examples of true cyclotron frequency measurements include detection of magnetron inter-harmonics of the reduced cyclotron frequency (i.e., the sidebands), trapping field-free (i.e., screened) ICR cells, and hyperbolic ICR cells with quadrupolar ion detection. More recently, ICR cells with spatially distributed ion clouds have demonstrated attractive performance characteristics for true cyclotron frequency ion detection. Here, we review the corresponding developments in FT-ICR MS over the past 40 years.

International audience; The UV-vis photodegradation of-tocopherol was investigated in a model system and in a cosmetic emulsion. Both gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) and high performance liquid chromatography coupled with ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (LC-UHR-MS) were used for photoproducts structural identification. Nine photoproduct families were detected and identified based on their mass spectra and additional experiments with-tocopherol-d 9 ; phototransformation mechanisms were postulated to rationalize their formation under irradiation. In silico QSAR (Quantitative Structure Activity Relationship) toxicity predictions were conducted with the Toxicity Estimation Software Tool (T.E.S.T.). Low oral rat LD50 values of 466.78 mg kg −1 and 467.9 mg kg −1 were predicted for some photoproducts, indicating a potential toxicity more than 10 times greater that of-tocopherol (5742.54 mg kg −1). In vitro assays on Vibrio fischeri bacteria showed that the global ecotoxicity of the-tocopherol solution significantly increases with irradiation time. One identified product should contribute to this ecotoxicity enhancement since in silico estimations for D. magna provide a LC50 value 4 times lower than that of the parent molecule.

The UV-visible photodegradation of Naproxen (6-methoxy-α-methyl-2-naphthaleneacetic acid, CAS: 22204-53-1), one of the most used and detected non-steroidal anti-inflammatory drugs (NSAIDs) in the world, and its ecotoxicological consequences were investigated in an aqueous medium. The photo-transformation products were analyzed and the structures of photoproducts were elucidated using gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) and high-performance liquid chromatography coupled with ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (LC-FTICR-MS). Seven photoproducts were detected and characterized, photo-transformation mechanisms have been postulated to rationalize their formation under irradiation. In silico Q.S.A.R. (Quantitative Structure-Activity Relationship) toxicity predictions were performed with the Toxicity Estimation Software Tool (T.E.S.T.) and in vitro assays were carried out on Vibrio fischeri bacteria. Some of the obtained photoproducts exhibit higher potential toxicity than Naproxen itself but the whole toxicity of the irradiated solution is not of major concern.

The photodegradation of benzisothiazolinone was studied in water under UV–Vis irradiation and led to fourteen photoproducts. Chemical structures of these compounds were elucidated using GC-MS, LCMS/MS, and FT-ICR-MS experiments. Based on the chemical structures determined and their appearance order, a photo induced-degradation mechanism of benzisothiazolinone has been proposed, which combines isomerization, oxidation, hydroxylation, hydrolysis, and elimination processes. In silico tests on mutagenicity, Fathead minnow LC50 and oral rat LD50 were carried out to estimate the toxicity of the photoproducts. Compared with experimental data, the calculated oral rat LD50 values were found to be the most relevant and thus used for toxicity estimation. The photoproducts including a phenolic or a sulfino group or both functions were found potentially more toxic than benzisothiazolinone.

Rationale Cyprodinil is a fungicide active on grapes, strawberries, tomatoes, and many other fruits. Under UV–visible irradiation, it undergoes photodegradation through various processes to form transformation products (TPs) whose structures and potential toxicities are unknown. The structures of the TPs were elucidated by comparing the photodegradation of cyprodinil and cyprodinil-D5. The potential toxicities of these compounds were compared with that of cyprodinil. Methods Aqueous solutions of cyprodinil were irradiated in a reactor equipped with a mercury vapor lamp. Analyses were carried out using high-performance liquid chromatography coupled to a quadrupole time-of-flight (QTOF) mass spectrometer or to a SolarixXR 9.4 Tesla Fourier transform (FT) mass spectrometer. High-resolution mass measurements, MS/MS and isotopic labeling experiments allowed structural elucidation of the cyprodinil TPs. The toxicities were estimated by three tests in silico using the TEST software and in vitro bioassays using Vibrio fischeri bacteria. These bioassays were carried out on irradiated solution for several exposure times and non-irradiated solutions. Results The structures of 19 photoproducts were characterized by LC/HRMS/MS after 4 h of irradiation of a cyprodinil aqueous solution. The use of cyprodinil-D5 allowed the TPs to be characterized with more confidence. Knowing the structure of the TPs allows the estimation of their potential toxicities by in silico tests. Most of the photoproducts are potentially more toxic than the parent compound, based on the oral rat LD50 values, and most of them might induce more developmental and mutagenic toxicities. In vitro assays on Vibrio fischeri bacteria showed that the global ecotoxicity of the cyprodinil solution significantly increases with irradiation time. Conclusions Structures of photoproducts were characterized after irradiation of a cyprodinil aqueous solution combining LC/HRMS, LC/HRMS/MS and the use of a labeled compound. Their formations imply several photodegradation reactions, namely direct bond cleavages, cyclization, isomerization and hydroxylation. Most of the TPs exhibit a toxicity significantly higher than that of the parent molecule. Copyright © 2016 John Wiley & Sons, Ltd.

International audience; Experimental infrared multiple-photon dissociation (IRMPD) spectra recorded for a series of deprotonated dicarboxylic acids, HO 2 (CH 2) n CO À 2 (n = 2-4), are interpreted using a variety of computational methods. The broad bands centered near 1600 cm À 1 can be reproduced neither by static vibrational calculations based on quantum chemistry nor by a dynamical description of individual structures using the many-body polar-izable AMOEBA force field, strongly suggesting that these molecules experience dynamical proton sharing between the two carboxylic ends. To confirm this assumption, AMOEBA was combined with a two-state empirical valence-bond (EVB) model to allow for proton transfer in classical molecular dynamics simulations. Upon suitable parametrization based on ab initio reference data, the EVB-AMOEBA model satisfactorily reproduces the experimental infrared spectra, and the finite temperature dynamics reveals a significant amount of proton sharing in such systems.

RATIONALE Metolachlor is one of the most intensively used chloroacetanilide herbicides in agriculture. It has been detected in water; consequently, under UV-visible irradiation, it can be transformed in degradation products (TPs). The structures of TPs were elucidated by liquid chromatography/high-resolution tandem mass spectrometry (LC/HR-MS/MS). The potential toxicities of these TPs were estimated by in silico tests. METHODS Aqueous solutions of metolachlor were irradiated in a self-made reactor equipped with a mercury vapor lamp. Analyses were carried out using high-performance liquid chromatography coupled to quadrupole time-of-flight (QTOF) mass spectrometer. High-resolution m/z measurements, MS/MS and isotopic labeling experiments allowed structural elucidation of metolachlor TPs. Their toxicities were estimated in silico, using the T.E.S.T. RESULTS Ten major metolachlor photoproducts were characterized by LC/MS/MS after irradiation of metolachlor in aqueous solution. Elucidation of their chemical structures was identified using high-resolution measurements and MS/MS experiments. They resulted from the combination of dehalogenation, hydroxylation and cyclisation processes. The potential oral rat lethal dose (LD50) was assessed with QSAR tests for metolachlor and each photoproduct. Results indicate that most of the TPs are much more toxic than metolachlor. CONCLUSIONS UV-vis irradiation of metolachlor in aqueous solution leads to the formation of ten photoproducts. QSAR estimations show that the location of added hydroxyl group(s) is of key relevance as regards to biological activity and that routine water analysis should take into account the TPs are more toxic than the parent molecule.

Rationale Fenbuconazole is a fungicide commonly used for the protection of vineyards, vegetables and grain crops. Under UV-visible irradiation, it undergoes isomerization through various cyclization processes. Isomeric structures were elucidated by liquid chromatography/high-resolution multiple-stage mass spectrometry (LC/HR-MSn) coupling. The potential toxicities of these isomers were estimated by in silico tests. Methods Aqueous solutions of fenbuconazole and grapes treated with this fungicide were irradiated in a self-made reactor equipped with a mercury vapor lamp. Analyses were carried out using high-performance liquid chromatography (HPLC) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICRMS). High-resolution m/z measurements, multiple-stage mass spectrometry and isotopic labeling experiments allowed structural elucidation of the isomers of fenbuconazole. In silico toxicity estimations were carried out using the T.E.S.T. program. Results Seven isomers of fenbuconazole were detected after irradiation of the fungicide in aqueous solution; the major ones were also detected in the flesh of treated grapes irradiated under laboratory conditions. Elucidation of their chemical structures owing to high resolution measurements and multi-stage collision induced dissociation experiments allowed confirmation of photo-transformation pathways mainly dominated by cyclization processes. Photo-induced isomers exhibited higher potential toxicities than fenbuconazole for Daphnia magna and fathead minnow species. Conclusions UV-visible irradiation of fenbuconazole in aqueous solution and on grapes leads to the formation of isomers, all of which being potentially much more toxic than the parent fungicide. Copyright © 2015 John Wiley & Sons, Ltd.

Ultraviolet (UV)–visible irradiation of fludioxonil was investigated with two photoreactors using either a mercury or xenon vapor lamp. In both cases, it led to the formation of only one photoproduct in significant amount: 2-(2,2-difluorobenzo[d][1,3]dioxol-4-yl)-2-(nitrosomethylene)-4-oxobutanenitrile, which has been characterized using Liquid Chromatography - High Resolution - Tandem Mass Spectrometry (LC-HR-MS/MS) coupling. A photolysis pathway has been proposed to rationalize its formation in degassed water. In vitro bioassays on Vibrio fischeri bacteria showed that UV–vis irradiation of an aqueous solution of fludioxonil significantly increases its toxicity. Because no other by-product was detected in significant amount, the photoproduct mentioned above may be considered mainly responsible for this increase in toxicity. Grape berries treated with a 50 ppm aqueous solution of fludioxonil were submitted to UV–visible irradiation under laboratory conditions. The fungicide and photoproduct were detected in both skin and flesh of berries, even after they have been rinsed with water. The ability of the photoproduct to pass through the fruit skin is comparable with that of fludioxonil. These results are of concern for consumers because they mean that water tap rinsing does not lead to efficient removing of both compounds. Copyright © 2015 John Wiley & Sons, Ltd.

International audience; This work aims to improve the computation of infrared spectra of gas-phase cations using DFT methods. Experimental IRMPD spectra for ten Zn and Ru organometallic complexes have been used to provide reference data for 64 vibrational modes in the 900-2000 cm-1 range. The accuracy of the IR vibrational frequencies predicted for these bands has been assessed over five DFT functionals and three basis sets. The functionals include the popular B3LYP and M06-2X hydrids and the range-separated hybrids (RSH) CAM-B3LYP, LC-BLYP and B97X-D. B3LYP gives the best mean absolute error (MAE) and root-mean-square error (RMSE) values of 7.1 and 9.6 cm-1 , whilst the best RSH functional, B97X-D, gives 12.8 and 16.6 cm-1 respectively. Using linear correlations instead of scaling factors improves the prediction accuracy significantly for all functionals. Experimental and computed spectra for a single complex can show significant differences even when the molecular structure is calculated correctly, and a means of defining confidence limits for any given computed structure is also provided.

Cyprodinil is a fungicide active on grapes, strawberries, tomatoes, and many other fruits. Under UV-visible irradiation, it undergoes photodegradation through various processes to form transformation products (TPs) whose structures and potential toxicities are unknown. The structures of the TPs were elucidated by comparing the photodegradation of cyprodinil and cyprodinil-D5 . The potential toxicities of these compounds were compared with that of cyprodinil.Aqueous solutions of cyprodinil were irradiated in a reactor equipped with a mercury vapor lamp. Analyses were carried out using high-performance liquid chromatography coupled to a quadrupole time-of-flight (QTOF) mass spectrometer or to a SolarixXR 9.4 Tesla Fourier transform (FT) mass spectrometer. High-resolution mass measurements, MS/MS and isotopic labeling experiments allowed structural elucidation of the cyprodinil TPs. The toxicities were estimated by three tests in silico using the TEST software and in vitro bioassays using Vibrio fischeri bacteria. These bioassays were carried out on irradiated solution for several exposure times and non-irradiated solutions.The structures of 19 photoproducts were characterized by LC/HRMS/MS after 4 h of irradiation of a cyprodinil aqueous solution. The use of cyprodinil-D5 allowed the TPs to be characterized with more confidence. Knowing the structure of the TPs allows the estimation of their potential toxicities by in silico tests. Most of the photoproducts are potentially more toxic than the parent compound, based on the oral rat LD50 values, and most of them might induce more developmental and mutagenic toxicities. In vitro assays on Vibrio fischeri bacteria showed that the global ecotoxicity of the cyprodinil solution significantly increases with irradiation time.Structures of photoproducts were characterized after irradiation of a cyprodinil aqueous solution combining LC/HRMS, LC/HRMS/MS and the use of a labeled compound. Their formations imply several photodegradation reactions, namely direct bond cleavages, cyclization, isomerization and hydroxylation. Most of the TPs exhibit a toxicity significantly higher than that of the parent molecule. Copyright © 2016 John WileySons, Ltd.

International audience; Studies of peptide fragment ion structures are important to aid in the accurate kinetic modeling and prediction of peptide fragmentation pathways for a given sequence. Peptide b(2)(+) ion structures have been of recent interest. While previously studied b(2)(+) ions that contain only aliphatic or simple aromatic residues are oxazolone structures, the HA b(2)(+) ion consists of both oxazolone and diketopiperazine structures. The structures of a series of histidine-analogue-containing Xxx-Ala b(2)(+) ions were studied by using action infrared multiphoton dissociation (IRMPD) spectroscopy, fragment ion hydrogen-deuterium exchange (HDX), and density functional theory (DFT) calculations to systematically probe the influence of different side chain structural elements on the resulting b(2)(+) ion structures formed. The b(2)(+) ions studied include His-Ala (HA), methylated histidine analogues, including π-methyl-HA and τ-methyl-HA, pyridylalanine (pa) analogues, including 2-(pa)A, 3-(pa)A, and 4-(pa)A, and linear analogues, including diaminobutanoic acid-Ala (DabA) and Lys-Ala (KA). The location and accessibility of the histidine π-nitrogen, or an amino nitrogen on an aliphatic side chain, were seen to be essential for diketopiperazine formation in addition to the more typical oxazolone structure formation, while blocking or removal of the τ-nitrogen did not change the b(2)(+) ion structures formed. Linear histidine analogues, DabA and KA, formed only diketopiperazine structures, suggesting that a steric interaction in the HisAla case may interfere with the complete trans-cis isomerization of the first amide bond that is necessary for diketopiperazine formation.

International audience; Infrared multiphoton dissociation (IRMPD) spectroscopy, using a free-electron laser, and ion mobility measurements, using both drift-cell and traveling-wave instruments, were used to investigate the structure of gas-phase peptide (AAHAL + 2H)(2+) ions produced by electrospray ionization. The experimental data from the IRMPD spectra and collisional cross section (Ω) measurements were consistent with the respective infrared spectra and Ω calculated for the lowest-energy peptide ion conformer obtained by extensive molecular dynamics searches and combined density functional theory and ab initio geometry optimizations and energy calculations. Traveling-wave ion mobility measurements were employed to obtain the Ω of charge-reduced peptide cation-radicals, (AAHAL + 2H)(+●), and the c(3), c(4), z(3), and z(4) fragments from electron-transfer dissociation (ETD) of (AAHAL + 2H)(2+). The experimental Ω for the ETD charge-reduced and fragment ions were consistent with the values calculated for fully optimized ion structures and indicated that the ions retained specific hydrogen bonding motifs from the precursor ion. In particular, the Ω for the doubly protonated ions and charge-reduced cation-radicals were nearly identical, indicating negligible unfolding and small secondary structure changes upon electron transfer. The experimental Ω for the (AAHAL + 2H)(+●) cation-radicals were compatible with both zwitterionic and histidine radical structures formed by electron attachment to different sites in the precursor ion, but did not allow their distinction. The best agreement with the experimental Ω was found for ion structures fully optimized with M06-2X/6-31+G(d,p) and using both projection approximation and trajectory methods to calculate the theoretical Ω values. © 2012 American Chemical Society

Fenbuconazole is a fungicide commonly used for the protection of vineyards, vegetables and grain crops. Under UV-visible irradiation, it undergoes isomerization through various cyclization processes. Isomeric structures were elucidated by liquid chromatography/high-resolution multiple-stage mass spectrometry (LC/HR-MS(n) ) coupling. The potential toxicities of these isomers were estimated by in silico tests.Aqueous solutions of fenbuconazole and grapes treated with this fungicide were irradiated in a self-made reactor equipped with a mercury vapor lamp. Analyses were carried out using high-performance liquid chromatography (HPLC) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICRMS). High-resolution m/z measurements, multiple-stage mass spectrometry and isotopic labeling experiments allowed structural elucidation of the isomers of fenbuconazole. In silico toxicity estimations were carried out using the T.E.S.T.Seven isomers of fenbuconazole were detected after irradiation of the fungicide in aqueous solution; the major ones were also detected in the flesh of treated grapes irradiated under laboratory conditions. Elucidation of their chemical structures owing to high resolution measurements and multi-stage collision induced dissociation experiments allowed confirmation of photo-transformation pathways mainly dominated by cyclization processes. Photo-induced isomers exhibited higher potential toxicities than fenbuconazole for Daphnia magna and fathead minnow species.UV-visible irradiation of fenbuconazole in aqueous solution and on grapes leads to the formation of isomers, all of which being potentially much more toxic than the parent fungicide.

International audience; The UV-vis photodegradation of iprodione in water was investigated with a high pressure mercury lamp photoreactor. Five photoproducts of iprodione were characterized by LC-HR-MS/MS and isotopic labeling ; none of them has been reported in previous studies. Three of them result from the elimination of one or two chlorine atoms followed by hydroxy or hydrogen addition while the two others are cyclic isomers of iprodione. An ICR mass spectrometer was used for by-products identification; concentrations of photoproducts were estimated with a triple quadrupole instrument, using iprodione-D 5 as an internal standard. Phototransformation mechanisms were postulated to rationalize photoproducts formation. In silico QSAR toxicity predictions were conducted with the Toxicity Estimation Software Tool (T.E.S.T.) considering oral rat LD50, mutagenicity and developmental toxicity. Low oral rat LD50 values of 350 mg/kg and 759 mg/kg were predicted for cyclic isomers of iprodione, compared to that of the parent molecule (2776 mg/kg). Toxicity estimations exhibited that all the iprodione photoproducts could be mutagenic while the parent compound is not. In vitro assays on Vibrio fischeri were achieved on both irradiated and non-irradiated aqueous solutions of iprodione and on HPLC fractions containing isolated photoproducts. Phenolic photoproducts were shown to be mainly responsible for toxicity enhancement with EC50 values of 0.3 and 0.5 ppm, for the bi-and mono-phenolic compounds issued from chlorine elimination.

Gas-phase infrared photodissociation spectroscopy is reported for the microsolvated [Mn(ClO(4))(H(2)O)(n)](+) and [Mn(2)(ClO(4))(3)(H(2)O)(n)](+) complexes from n = 2 to 5. Electrosprayed ions are isolated in an ion-trap where they are photodissociated. The 2600-3800 cm(-1) spectral region associated with the OH stretching mode is scanned with a relatively low-power infrared table-top laser, which is used in combination with a CO(2) laser to enhance the photofragmentation yield of these strongly bound ions. Hydrogen bonding is evidenced by a relatively broad band red-shifted from the free OH region. Band assignment based on quantum chemical calculations suggest that there is formation of water-perchlorate hydrogen bond within the first coordination shell of high-spin Mn(II). Although the observed spectral features are also compatible with the formation of structures with double-acceptor water in the second shell, these structures are found relatively high in energy compared with structures with all water directly bound to manganese. Using the highly intense IR beam of the free electron laser CLIO in the 800-1700 cm(-1), we were also able to characterize the coordination mode (eta(2)) of perchlorate for two clusters. The comparison of experimental and calculated spectra suggests that the perchlorate Cl-O stretches are unexpectedly underestimated at the B3LYP level, while they are correctly described at the MP2 level allowing for spectral assignment.

International audience