Electrocatalysis at vegetable oil water interface

Biphasic oxygen reduction and hydrogen evolution are studied for almost two decades, because of favourable overpotential decrease as compared to aqueous solution. Until now, polar solvents (ε > 7) were employed as organic phase in these studies. Here, we applied non polar vegetable oils (rapeseed, linen or sunflower) for biphasic H2O2 generation by oxygen reduction. This product was detected at oil|aqueous acid solution interface by scanning electrochemical microscopy, when electron donor – decamethylferrocene, was electrochemically recycled. Ejection of small fraction of decamethylferrocenium cation from oil to aqueous phase was also noticed

Silver nanoparticle accumulation by aquatic organisms – neutron activation as a tool for the environmental fate of nanoparticles tracing

Water environments are noted as being some of the most exposed to the influence of toxic nanoparticles (NPs). Therefore, there is a growing need for the investigation of the accumulation and toxicity of NPs to aquatic organisms. In our studies neutron activation followed by gamma spectrometry and liquid scintillation counting were used for studying the accumulation of silver nanoparticles (AgNPs) by freshwater larvae of Chironomus and fish Danio rerio. The influence of exposition time, concentration and the source of nanoparticles on the efficiency of AgNP accumulation were studied. It was found that AgNPs are efficiently accumulated by Chironomid larvae for the first 30 hours of exposition; then, the amount of silver nanoparticles decreases. The silver content in larvae increases together with the NP concentration in water. Larvae which have accumulated AgNPs can be a source of nanoparticles for fish and certainly higher levels of Ag in the trophic chain. In comparison with water contamination, silver nanoparticles are more efficiently accumulated if fish are fed with AgNP-contaminated food. Finally, it was concluded that the applied study strategy, including neutron activation of nanoparticles, is very useful technique for tracing the uptake and accumulation of NPs in organism

Uptake, translocation, size characterization and localization of cerium oxide nanoparticles in radish (Raphanus sativus L.)

International audienceDue to their unique physical and chemical properties, the production and use of cerium oxide nanoparticles (CeO 2 NPs) in different areas, especially in automotive industry, is rapidly increasing, causing their presence in the environment. Released CeO 2 NPs can undergo different transformations and interact with the soil and hence with plants, providing a potential pathway for human exposure and leading to serious concerns about their impact on the ecosystem and human organism. This study investigates the uptake, bioaccumulation, possible translocation and localization of CeO 2 NPs in a model plant (Raphanus sativus L.), whose edible part is in direct contact with the soil where contamination is more likely to happen. The stability of CeO 2 NPs in plant growth medium as well as after applying a standard enzymatic digestion procedure was tested by single particle ICP-MS (SP-ICP-MS) showing that CeO 2 NPs can remain intact after enzymatic digestion; however, an agglomeration process was observed in the growth medium already after one day of cultivation. An enzymatic digestion method was next used in order to extract intact nanoparticles from the tissues of plants cultivated from the stage of seeds, followed by size characterization by SP-ICP-MS. The results obtained by SP-ICP-MS showed a narrower size distribution in the case of roots suggesting preferential uptake of smaller nanoparticles which led to the conclusion that plants do not take up the CeO 2 NPs agglomerates present in the medium. However, nanoparticles at higher diameters were observed after analysis of leaves plus stems. Additionally, a small degree of dissolution was observed in the case of roots. Finally, after CeO 2 NPs treatment of adult plants, the spatial distribution of intact CeO 2 NPs in the radish roots was studied by laser ablation ICP-MS (LA-ICP-MS) and the ability of NPs to enter and be accumulated in root tissues was confirmed

Elucidation of the fate of zinc in model plants using single particle ICP-MS and ESI tandem MS

International audienceIn recent years, the increasing use of zinc oxide nanoparticles (ZnO NPs) in many consumer products and industrial applications made them a new potential source of zinc in the environment. After their release into the environment, ZnO NPs can undergo different transformations which are still poorly understood and may influence their potential toxicity. This study investigates for the first time the fate of zinc, supplied in the form of ZnO NPs and ZnCl2, taken up by a model edible plant (lettuce, Lactuca sativa L.) by means of different mass spectrometry techniques. Single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) analysis showed the rapid dissolution of ZnO NPs in the growth medium used for cultivation of lettuce, confirming that only dissolved zinc, not intact NPs, is taken up by plants. Taking into account that the beneficial or toxic effects of zinc depend on its form accumulated by plants, it is crucial to identify the chemical forms of zinc and their distribution in edible plant tissues. Therefore, the second part of this work was focused on the study of zinc speciation in plants cultivated with ZnCl2 by using hyphenated techniques. The proposed approach based on two-dimensional chromatographic (size exclusion – SEC and hydrophilic interaction – HILIC) separation with parallel ICP-MS and ESI-qTOF-MS/ESI-FT-Orbitrap-MS detection allows the determination and identification of minor zinc complexes at environmentally relevant concentrations. Nicotianamine (NA) is shown to be the major ligand binding zinc in lettuce leaves, and the Zn–NA complex is responsible for more than 70% of the total zinc content extracted from lettuce leaves by means of ammonium acetate buffer

Newly Discovered Components of Dendrolimus pini Sex Pheromone

The pine-tree lappet moth, D. pini, is a harmful defoliator of pine forests in Europe and Asia and a potentially invasive species in North America. The lures for trapping D. pini males based on two known components of its sex pheromone appeared weakly attractive to male moths. Identification of all components of the sex pheromone might allow for the development of more effective lures. The pheromone was sampled from virgin females using SPME and analyzed using gas chromatography coupled with mass spectrometry. Four new likely components ((Z5)-dodecenal, (Z5)-dodecen-1-ol, (Z5)-decen-1-yl acetate, (Z5)-tetradecen-1-yl acetate) and two known components ((Z5,E7)-dodecadienal, (Z5,E7)-dodecadien-1-ol) were identified based on comparison against authentic standards, Kováts indices and spectra libraries. The samples also contained several sesquiterpenes. Wind tunnel and field experiments showed that some blends of synthetic pheromone components alone or enriched with Scots pine essential oil (SPEO) were attractive to D. pini males. One component—(Z5)-decen-1-yl acetate—had a repelling effect. The presented knowledge of D. pini sex pheromone provides a basis for developing optimal lures for monitoring or controlling insect populations

Detection of fungi and oomycetes by volatiles using E-nose and SPME-GC/MS platforms

Fungi and oomycetes release volatiles into their environment which could be used for olfactory detection and identification of these organisms by electronic-nose (e-nose). The aim of this study was to survey volatile compound emission using an e-nose device and to identify released molecules through solid phase microextraction–gas chromatography/mass spectrometry (SPME–GC/MS) analysis to ultimately develop a detection system for fungi and fungi-like organisms. To this end, cultures of eight fungi (Armillaria gallica, Armillaria ostoyae, Fusarium avenaceum, Fusarium culmorum, Fusarium oxysporum, Fusarium poae, Rhizoctonia solani, Trichoderma asperellum) and four oomycetes (Phytophthora cactorum, P. cinnamomi, P. plurivora, P. ramorum) were tested with the e-nose system and investigated by means of SPME-GC/MS. Strains of F. poae, R. solani and T. asperellum appeared to be the most odoriferous. All investigated fungal species (except R. solani) produced sesquiterpenes in variable amounts, in contrast to the tested oomycetes strains. Other molecules such as aliphatic hydrocarbons, alcohols, aldehydes, esters and benzene derivatives were found in all samples. The results suggested that the major differences between respective VOC emission ranges of the tested species lie in sesquiterpene production, with fungi emitting some while oomycetes released none or smaller amounts of such molecules. Our e-nose system could discriminate between the odors emitted by P. ramorum, F. poae, T. asperellum and R. solani, which accounted for over 88% of the PCA variance. These preliminary results of fungal and oomycete detection make the e-nose device suitable for further sensor design as a potential tool for forest managers, other plant managers, as well as regulatory agencies such as quarantine services