Development and validation by accuracy profile of a method for the analysis of monoterpenes in indoor air by active sampling and thermal desorption-gas chromatography-mass spectrometry

peer reviewedThe technique of thermal desorption (TD)-GC/MS was evaluated for the measurement of monoterpenes in indoor air. The validation strategy was intentionally oriented towards routine use and the reliability of the method rather than extreme performance. For this reason, validation by accuracy profile was chosen. The accuracy profile procedure, which is based on the concept of total error (bias + standard deviation), guarantees that a known proportion of future results obtained with the method will be within acceptance limits. For all the compounds tested in the present study, α-pinene, α-terpineol, β-pinene, d-limonene, Δ3-carene, camphene, 1,8-cineole, p-cymene, linalool, but not in the case of carvone, the accuracy profile procedure established that at least 95% of the future results obtained would be within the ±15% acceptance limits of the validated method over the whole defined concentration range. Other parameters, such as selectivity, recovery, repeatability, stability of the molecules of interest and the effect of temperature, were also determined. The performance of the described method was finally evaluated by the analysis of indoor air from new timber frame constructions

Olfactory responses to aphid and host plant volatile releases: (E)-beta-farnesene an effective kairomone for the predator Adalia bipunctata.

peer reviewedThe volatiles released from several aphid and host plant species, alone or associated, were studied for their infochemical role in prey location. Using a four-arm olfactometer, the attraction of several combinations of three aphid (Myzus persicae, Acyrthosiphon pisum, and Brevicoryne brassicae) and three plant (Vicia faba, Brassica napus, and Sinapis alba) species toward Adalia bipunctata larvae and adults was observed. Both predatory larvae and adults were attracted only by A. pisum and M. persicae when they were crushed, whatever the host plant. (E)-beta-farnesene, the aphid alarm pheromone, was the effective kairomone for the ladybird. Plant leaves alone (V. faba, B. napus, and S. alba) or in association with nonstressed whole aphids (the three species) did not have any attraction for the predator. The B. brassicae specialist aphid is the only prey that was not attracted to A. bipunctata larvae and adults, even if they were crushed. Release of B. brassicae molecules similar to the host plant allelochemicals was demonstrated by GC-MS analysis. The lack of behavioral response of the ladybird at short distance toward the cruciferous specialist aphid was related only to the absence of (E)-beta-farnesene in the aphid prey volatile pattern

Hoverfly glutathione S-transferases and effect of Brassicaceae secondary metabolites

The Episyrphus balteatus hoverfly is commonly found in very diversified biotopes including Brassicaceae crop fields. Glutathione S-transferases (GST) are detoxification enzymes that are involved in the metaboliza-tion of plant allelochemicals such as glucosinolates and related volatile products (mainly isothiocyanates) from Brassica plants. Developmental expression of E. balteatus glutathione S-transferases was studied. With regard to the high level of glutathione S-transferase activity in syrphid adults, the latter stage was also used to assess the glutathione S-transferase distribution in several parts of the insect. Higher glutathione S-transferase activities were found in the thorax (47.5 and 38.5%) followed by the abdomen (32.4 and 32.9%) and the head (20.4 and 28.5%) with l-chloro-2,4-dinitrobenzene, and 2,4-dinitro-l-iodebenzene, respectively. Analysis of Brevicoryne brassicae, the cabbage aphid, by GC-MS revealed the presence of isothiocyanates. The latter are the main degradation products of the glucosinolate from the host plant at neutral pH. Feeding the predators with this aphid species and with the generalist Myzus persicae reared on Brassica napus induced glutathione S-transferase activity. Impact of volatiles from the host plant on the glutathione S-transferase activity was also determined by exposure of syrphid larvae to isothiocyanates (allyl- and benzyl-isothiocyanates). Enzyme inductions were observed only from a 1 ppm concentration. Enzymatic activity evolution was discussed as an adaptation to cope with allelochemicals from plants. Finally, the glutathione 5-transferase activities of several hoverfly species were compared in relation to their feeding behavior (coprophagous, saprophagous, and aphidophagous) at the larval stages. The results seem to indicate quantitative and qualitative differences of glutathione S-transferases according to the feeding behavior of the larvae

Investigating the Effects of Plant Root Exudates on PAHs Bioavailability to Soil Microorganisms in Contaminated Brownfields : Research Methodology.

As a result of heavy industrial past activities, an estimated 6,000 brownfields require remediation in Wallonia. This number rises to over 3.5 million in Europe. Polycyclic Aromatic Hydrocarbons (PAHs) represent 17% of treated pollutants in Wallonia (Aldric et al., 2011). Current remediation techniques are rather expensive and technically demanding (Megharaj et al., 2011). Based on the observation that PAHs soil content decreases in the presence of plants (Cheema et al., 2010), the PhD aims at developing alternative PAHs remediation techniques in brownfields. It is articulated around three research axes. The first axis focusses on plant exudates and how they may improve PAHs bioavailability to soil microorganisms and enhance their degradation. This will be investigated by (i) characterizing several contaminated soils (physico-chemical parameters) and PAH content and factors of bioavailability, (ii) selecting a plant model and collecting root exudates, and (iii) evaluating the effects of exudates on PAHs bioavailability. The objective of the second axis is to evaluate the effects of plant exudates on PAHs degrading microorganisms by (i) comparing PAHs biodegradation in the presence/absence of exudates and (ii) assessing the potential toxic effects of exudate compounds on the microbial communities. The aim of the third axis is to study plant-pollutants interactions by (i) establishing the plant tolerance to several contamination levels and (ii) following PAHs bioavailability when facing real exudation rates, on the field

Analytical methods used to quantify isoflavones in cow's milk: a review

peer reviewedThis paper provides an update and comprehensive review of the analytical methods used for quantifying isoflavones and their metabolites in cow’s milk. Isoflavones are secondary plant metabolites that are similar to 17 β-estradiol in chemical structure. They form one of the most common categories of phytoestrogens. Numerous health benefits have been attributed to isoflavones, but many of these compounds are also considered to be endocrine disruptors, with adverse effects on health. These contradictory trends offer an attractive prospect for future research, and therefore, sensitive and reliable analytical methods are required to clarify various issues about isoflavones. For this review, a structured methodology was used to select 26 relevant articles published between 2005 and 2015 from the Scopus and CAB Abstract databases. The review discusses individual steps of the analytical procedures described in these articles, including sample preparation, instrumental analysis and validation. The most commonly used analytical procedure is sample preparation involving liquid-liquid extraction and an enzymatic hydrolysis step followed by liquid chromatography with mass spectrometry analysis. Currently, however, there is no standardized procedure for the sample preparation and analysis of isoflavones in milk.PhytoHealt

Comment les insectes communiquent-ils au sein de l’ «écosystème-cadavre» ? L’écologie chimique des insectes nécrophages et nécrophiles

L’entomologie forensique est une discipline des sciences forensiques qui étudie les insectes et d’autres arthropodes dans un contexte médico-légal. Les insectes nécrophages et nécrophiles, principalement des Diptères et des Coléoptères, sont fréquemment retrouvés au sein de l’écosystème-cadavre. Pour ces insectes, le cadavre est une ressource éphémère très riche qu’ils vont coloniser de manière plus ou moins prévisible. L’entomofaune des cadavres seraient attirées par les odeurs cadavériques émises par le corps en décomposition. A l’heure actuelle, la thanatochimie est encore peu étudiée et l’information disponible concernant les COVs émis après la mort est limitée. Grâce à l’utilisation des méthodes de chimie analytique (TDS)GC-MS, GCxGC-TOF-MS), la signature olfactive d’un cadavre peut être étudiée au cours du processus de décomposition. L’ « odeur de la mort » est constituée par un mélange de plus de cent composés organiques volatils qui évoluent au cours de la décomposition. Cependant, les sémiochimiques qui sont réellement attractifs pour les insectes nécrophages et/ou nécrophiles ne sont pas encore clairement identifiés. Les espèces pionnières pourraient être attirées par des COVs cadavériques. Toutefois, les espèces plus tardives pourraient aussi être attirées par d’autres types de sémiochimiques produits par les insectes sarcosaprophages eux-mêmes (par exemple : des asticots, des insectes nécrophages). Plusieurs techniques d’écologie chimique peuvent être utiles en vue d’investiguer le rôle des sémiochimiques cadavériques dans le comportement des insectes sarcosaprophages. Une meilleure compréhension de l’écologie chimique des insectes nécrophages/nécrophiles et la thanatochimie pourraient avoir de nombreuses applications en science forensique et plus particulièrement en entomologie forensique

Matar a un ruiseñor

Abstract not availabl

Ophioglossum polyphyllum A. Braun in Seub. (Ophioglossaceae, Pteridophyta), a rare potherb in south central Tibet (T.A.R., P.R.China)

peer reviewe

Contribution to the study of semiochemical slow release formulations. Development of flash chromatographic methods

Peer reviewe