Jean-Luc Besombes

A biosensor as warning device for the detection of cyanide, chlorophenols, atrazine and carbamate pesticides

Abstract The determination of cyanide, chlorophenols, atrazine, dithiocarbamate and carbamate pesticides is described, utilizing an amperometric biosensor constructed by the electropolymerization of a pyrrole amphiphilic monomer-tyrosinase coating. Measurements were carried out with catechol, dopamine, l -DOPA or epinephrine as an enzyme substrate; the enzymatically generated quinoid products being electroreduced at -200 mV vs. SCE. The detection of these water pollutants was performed via their inhibiting action on the tyrosinase electrode. The characterization of the inhibition processes (competitive /non-competitive) and their reversibility were examined. The detection limits are 0.4, 2, 2, 4 and 0.02 μM for 3,4-dichlorophenol, chloroisopropylphenylcarbamate, 3-chloroaniline, atrazine and cyanide, respectively.

Improvement of the analytical characteristics of an enzyme electrode for free and total cholesterol via laponite clay additives

Abstract The electropolymerization of a laponite nanoparticle-amphiphilic pyrrole derivative-enzyme mixture preadsorbed on the electrode surface provides simultaneously the immobilization of the enzyme and the laponite particles in the polypyrrolic matrix. These incorporated laponite nanoparticles greatly enhance the sensitivity and stability of a cholesterol oxidase-based biosensor. Compared to a similar biosensor without laponite, the biosensor sensitivity increased from 5.1 to 13.2 mA M −1 cm −2 . Furthermore, the presence of hydrophilic laponite additive in the polymeric matrix containing cholesterol oxidase and cholesterol esterase is essential for the successful determination of total cholesterol.

Determination of phenol and chlorinated phenolic compounds based on a PPO-bioelectrode and its inhibition

Abstract A polyphenol oxidase (PPO) enzyme electrode constructed by the electropolymerization of a pyrrole amphiphilic monomer-PPO mixture, previously adsorbed on a glassy carbon electrode, is applied for the direct amperometric response of phenol, 3-chlorophenol and 4-chlorophenol. Furthermore, the detection of 2-chlorophenol, several polychlorophenols and pentachlorophenol is carried out by an inhibition process of the bioelectrode functioning. The mechanism of the bioelectrode inhibition is investigated in terms of enzymatic inhibition and polymer fouling. The capacities of this system for the resolution of mixtures of phenolic pollutants are also explored on the basis of the kinetic behavior of the bioelectrode response.

Source apportionment of PM10, organic carbon and elemental carbon at Swiss sites: An intercomparison of different approaches

In this study, the results of source apportionment of particulate matter (PM10), organic carbon (OC), and elemental carbon (EC) - as obtained through different approaches at different types of sites (urban background, urban roadside, and two rural sites in Switzerland) - are compared. The methods included in this intercomparison are positive matrix factorisation modelling (PMF, applied to chemical composition data including trace elements, inorganic ions, OC, and EC), molecular marker chemical mass balance modelling (MM-CMB), and the aethalometer model (AeM). At all sites, the agreement of the obtained source contributions was reasonable for OC, EC, and PM10. Based on an annual average, and at most of the considered sites, secondary organic carbon (SOC) is the component with the largest contribution to total OC; the most important primary source of OC is wood combustion, followed by road traffic. Secondary aerosols predominate in PM10. All considered techniques identified road traffic as the dominant source of EC, while wood combustion emissions are of minor importance for this constituent. The intercomparison of different source apportionment approaches is helpful to identify the strengths and the weaknesses of the different methods. Application of PMF has limitations when source emissions have a strong temporal correlation, or when meteorology has a strong impact on PM variability. In these cases, the use of PMF can result in mixed source profiles and consequently in the under- or overestimation of the real-world sources. The application of CMB models can be hampered by the unavailability of source profiles and the non-representativeness of the available profiles for local source emissions. This study also underlines that chemical transformations of molecular markers in the atmosphere can lead to the underestimation of contributions from primary sources, in particular during the summer period or when emission sources are far away from the receptor sites.

Effect of the chemical composition of organic extracts from environmental and industrial atmospheric samples on the genotoxicity of polycyclic aromatic hydrocarbons mixtures

Particulate organic matter (PM) present in the atmosphere is a complex mixture of chemicals like polycyclic aromatic hydrocarbons (PAH) that may exert adverse health effects including respiratory and cardiovascular disturbances and cancer. In this study, airborne samples from environmental or industrial areas exhibiting different physicochemical composition were compared for their capacities to induce DNA damage in human hepatocytes HepG2. DNA strand breaks and DNA adducts formed by benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE), the most reactive metabolite of the carcinogenic benzo[a]pyrene (B[a]P), were measured with the comet assay and by high-performance liquid chromatography (HPLC)/mass spectrometry, respectively. Cells were exposed to organic matter extracted from PM. Experiments were performed either at a constant concentration of B[a]P or at concentrations corresponding to fixed air volumes. Results show that industrial extracts tend to produce more benzo[a]pyrene diol epoxide-N 2-2′-deoxyguanosine (BPDE-N 2-dGuo) DNA adducts than strand breaks, whereas the opposite was observed with environmental extracts. The chemical composition of the extracts significantly impacts the nature and levels of DNA damage. The amount of B[a]P and interaction with other contaminants in the extracts need to be considered to explain the formation of DNA damage. These results emphasize the use of in vitro tests as promising and complementary tools to widely used toxic equivalent factor (TEF) approach in order to assess health hazards related to chemical exposure of the general population.

Speciation of organic fraction does matter for source apportionment. Part 1: A one-year campaign in Grenoble (France)

PM10 source apportionment was performed by positive matrix factorization (PMF) using specific primary and secondary organic molecular markers on samples collected over a one year period (2013) at an urban station in Grenoble (France). The results provided a 9-factor optimum solution, including sources rarely apportioned in the literature, such as two types of primary biogenic organic aerosols (fungal spores and plant debris), as well as specific biogenic and anthropogenic secondary organic aerosols (SOA). These sources were identified thanks to the use of key organic markers, namely, polyols, odd number higher alkanes, and several SOA markers related to the oxidation of isoprene, α-pinene, toluene and polycyclic aromatic hydrocarbons (PAHs). Primary and secondary biogenic contributions together accounted for at least 68% of the total organic carbon (OC) in the summer, while anthropogenic primary and secondary sources represented at least 71% of OC during wintertime. A very significant contribution of anthropogenic SOA was estimated in the winter during an intense PM pollution event (PM10>50μgm-3 for several days; 18% of PM10 and 42% of OC). Specific meteorological conditions with a stagnation of pollutants over 10days and possibly Fenton-like chemistry and self-amplification cycle of SOA formation could explain such high anthropogenic SOA concentrations during this period. Finally, PMF outputs were also used to investigate the origins of humic-like substances (HuLiS), which represented 16% of OC on an annual average basis. The results indicated that HuLiS were mainly associated with biomass burning (22%), secondary inorganic (22%), mineral dust (15%) and biogenic SOA (14%) factors. This study is probably the first to state that HuLiS are significantly associated with mineral dust.