Marie-Florence Grenier-Loustalot

Multi-residue analysis of steroids at sub-ng/L levels in surface and ground-waters using liquid chromatography coupled to tandem mass spectrometry

Most analytical methodologies currently available for the determination of steroids in water only identify a few representative compounds (mainly estrogens). In this context, a multi-residue methodology based on liquid chromatography-tandem mass spectrometry was developed for the determination of 26 steroids including natural and synthetic estrogens, progestagens and androgens. The method described involves limited sample preparation as it includes a filtration followed by a single solid-phase extraction step using a C18 cartridge. The analytical procedure allows the determination of the target analytes in the lower ng/L range, with recoveries above 80%. The methodology was successfully applied to the analysis of steroids in several surface and ground-waters. In all the waters, estrogens, androgens and/or progestagens were determined.

Phenolic resins: 2. Influence of catalyst type on reaction mechanisms and kinetics

We have investigated the influence of the type of basic catalyst on the mechanisms and kinetics of phenolformaldehyde reactions in perfectly controlled conditions of synthesis (temperature, stoichiometry and pH). The results obtained using liquid-state physicochemical analysis techniques, such as high performance liquid chromatography, 13C nuclear magnetic resonance spectroscopy and chemical assays, indicate that the nature of the basic catalyst affects the mechanisms and kinetics of condensation and thus the composition of the reaction medium. The results show that the valence and ionic radius of hydrated cations affect the changes of species in the reaction medium. The catalysts were classified into two families as a function of their behaviour: KOH, NaOH and LiOH, and Ba(OH)2 and Mg(OH)2. We have found the formation of certain monomers and dimers, particularly ortho-substituted species.

Phenolic resins: 1. Mechanisms and kinetics of phenol and of the first polycondensates towards formaldehyde in solution

Abstract Using chemically defined compounds (first reaction product intermediates of the phenol-formaldehyde system), we have studied the reaction mechanisms of formaldehyde condensation in perfectly controlled conditions (temperature, stoichiometry, catalyst and pH). The results obtained with a range of techniques, e.g. high-performance liquid chromatography, 13C nuclear magnetic resonance and chemical assay, show that the reaction kinetics and the structures of the resole end-products depend on synthetic and operating conditions.

Phenolic resins: 5. Solid-state physicochemical study of resoles with variable FP ratios

Abstract We have studied the reactions occuring in the solid state in phenol-formaldehyde systems crosslinked by a base. The results obtained with chemically defined models with Fourier transform infra-red spectroscopy and solid-state 13 C nuclear magnetic resonance spectroscopy (cross-polarization/magic angle spinning) applied the study of different resoles with variable formaldehyde/phenol ratios have shown that changes in the prepolymer can be followed after the gel point. Nevertheless, data obtained on the final structure of the system indicate that the fine characterization of the prepolymer before the gel point must be conducted in the study of these complex systems.

Multi-residue analysis and ultra-trace quantification of 36 priority substances from the European Water Framework Directive by GC-MS and LC-FLD-MS/MS in surface waters.

A multi residue analysis was developed for screening, quantification and confirmation of 36 priority organic compounds included in the 2000/60/EC European Water Framework Directive. The compounds analyzed included 19 pesticides, 8 PAH, 5 endocrine-disruptors and 4 organochlorine compounds. The method was developed in three steps. First, automated off-line solid-phase extraction using Strata X cartridges was optimized to trap simultaneously the 36 studied compounds. Second, the more volatile compounds were analysed by gas chromatography coupled to mass spectrometry with electron impact ionisation in selected ion monitoring mode (SIM). Third, the last 20 compounds were detected and quantified, in one run, by liquid chromatography coupled to fluorescence detector and tandem mass spectrometry. The excellent selectivity and sensitivity allowed us satisfactory quantification and confirmation at levels as low as 0.2-67 ng L(-1) with recoveries between 59 and 105%. Such methodology was then applied to French surface waters: all the waters present organic contaminants, and their concentration varied according to the origin and nature of substances.

Phenolic resins: 4. Self-condensation of methylolphenols in formaldehyde-free media

Abstract Using kinetic and mechanistic monitoring by high-performance liquid chromatography and 13 C nuclear magnetic resonance, we have shown that in formaldehyde-free conditions the reactivity of substituted phenols towards condensation reactions arises from several factors. In particular, the groups reacting among themselves may be of two types: either a non-substituted ortho or para aromatic carbon, or the methylene carbon of a hydroxymethyl group. In addition to the difference in the nature of the group, its position on the aromatic ring is predominant, and the reaction in the para position is favoured. Thus, a third factor participates in the mechanism and kinetics of reaction: the ionization constant of the phenol, which increases with the substitution of phenol and favoured the formation of phenate. We thus show that, in the conditions chosen, two reaction mechanisms participate and the reactivity of sites depends on ring substitution by hydroxymethyl groups.

Phenolic resins: 3. Study of the reactivity of the initial monomers towards formaldehyde at constant pH, temperature and catalyst type

We have studied the addition of formaldehyde to the various phenolic monomers present in a phenolformaldehyde system under conditions of constant temperature, pH and catalyst type. The techniques used, carbon-13 nuclear magnetic resonance and high-performance liquid chromatography, enabled us to show the effect of aromatic ring substitution on the reactivity of sites that can potentially react. We have shown from a mechanistic standpoint that the aromatic carbon in the para position is more reactive towards formaldehyde or a hydroxymethyl group than the aromatic carbon in the ortho position. Condensation reactions involving the para hydroxymethyl group preferentially lead to the formation of compounds with a para-para methylene bridge. From a kinetic standpoint, we have demonstrated that changes in each monomer as a function of time enable the order of reactivity of these compounds towards formaldehyde to be determined under the conditions of temperature, pH and concentration employed.

Influence of the stoichiometry of epoxy‐cyanate systems (non‐catalyzed and catalyzed) on molten state reactivity

Based on an FT-IR and 13C-NMR spectroscopic study using model compounds, we previously proposed an epoxy-cyanate coreaction path in the molten state, by identifying all chemical species and their role in the reaction mixture. These data were then applied to difunctional systems involving diglycidyl ether of bisphenol A (DGEBA) and bisphenol A dicyanate (BADCy), with mixtures prepared in different epoxy/cyanate ratios. Using FT-IR and solid state 13C-NMR spectroscopic analyses, we show the effect of epoxy group concentration on the final structure of the system. We were able to show that epoxy functions react on the triazine rings formed in the first step of homopolymerization of cyanates, and that the structure of the final system depends on their initial concentration. In addition, a study of difunctional systems for identical cyanate-epoxy stoichiometry was undertaken in the presence of anionic (imidazole) and metallic (AcAcCu and AcAcCr) catalysts in order to determine their effect on the reactivity of the two monomers and on the structure of the final system.

Comparison of the analysis of β-blockers by different techniques

In this work we have compared three analytical techniques (ELISA, GC-MS, and LC-MS) for the analysis of 16 beta-blockers: acebutolol, alprenolol, atenolol, betaxolol, bisoprolol, carteolol, labetalol, metipranolol, metoprolol, nadolol, oxprenolol, pindolol, propranolol, sotalol, timolol, and bupranolol. Several sample-preparation methods were optimized for each technique and enabled compounds of interest to be extracted from small urine samples (1-2.5 mL). The results enabled us to assess the possibilities and the sensitivity of each technique for application to doping tests. ELISA, whose selectivity is very poor and sensitivity the lowest one, is, nevertheless, useful as a rapid screening method. GC/MS and LC/MS provide confirmation procedures with the identification and quantification of the beta-blockers with good sensitivity, accuracy, precision. The LC-MS analytical procedure allows the determination of the target analytes in the lower ng/mL range (0.53-2.23 ng/mL). The methodology was applied to the analysis of beta-blockers in different urines.

A study of the mechanisms and kinetics of the molten state reaction of non-catalyzed cyanate and epoxy-cyanate systems

Abstract Molten state epoxy-eyanate reactions using non-catalyzed monofunctional models were analyzed in the temperature range of 150–250 °C. In comparison to results obtained with paracurnyl phenyl cyanate (CPCy), the present findings enabled the detection of four-membered ring and carbamate intermediates that autocatalyzed the reaction. Conclusions could be drawn only after preparative HPLC separation of the different fractions and analysis by 13 C-NMR, 1 H-NMR and FTIR. A new reaction path is proposed for these systems.