Discrimination of geographical origin of rice based on multi-element fingerprinting by high resolution inductively coupled plasma mass spectrometry

International audienceRice is a staple food for nearly half the world’s population. The discrimination of geographical origin of rice in order to its authenticity is essential to prevent mislabeling and adulteration problems. The multi-element fingerprinting has a great potential for the differentiation of rice grains. A study of the capability of the high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) methodology for multi-element fingerprinting of rice has been carried out. A total of 31 Thai jasmine rice and 5 foreign (France, India, Italy, Japan and Pakistan) rice samples were analysed by high resolution ICP-MS after acid digestion. Accuracy of the whole procedure was verified by the analysis of rice flour standard reference material (NIST SRM 1568a). The concentrations of 21 elements were evaluated and used as chemical indicator to discriminate the origin of rice samples. The classification of rice samples was carried out based on elemental composition by a radar plot and multivariate data analysis, including principal component analysis (PCA) and discriminant analysis (DA). Thai jasmine rice can be differentiated from foreign rice samples by radar plots and multivariate data analysis. Furthermore, the DA can differentiate Thai jasmine rice samples according to each region of origin (northern, northeastern or central regions of Thailand). Therefore, multi-element fingerprinting combined with the use of multivariate statistical techniques can be considered as a powerful tool for rice authentication

Large-scale speciation of selenium in rice proteins using ICP-MS assisted electrospray MS/MS proteomics

International audienceA Se-targeted bottom-up proteomics approach was developed for the identification of Se-containing proteins in rice grown naturally on seleniferous soils. The proteins were separated by 2D gel electrophoresis. The position of Se-containing spots was tentatively identified by the correlation between the 1D isoelectrofocusing (IEF) and 1D SDS electropherograms of a sample aliquot and confirmed by 78Se imaging in the 2D gel. The method was complemented by the ICP-MS assisted shotgun proteomics approach. The proteins were identified by capHPLC with the dual ICP MS and electrospray Orbitrap MS detection. The first ever comprehensive study of rice selenoproteome revealed the presence of selenium, as both selenomethionine (SeMet) and selenocysteine (SeCys) residues, in a dozen proteins including a 19 kDa globulin, granule-bound starch synthase, and the family of glutelin-type seed storage proteins

Mise au point d'une analyse multi-résidus de produits phytosanitaires dans les miels, les abeilles et le pollen par LC-MS/MS et GC-ToF

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Monitoring of twenty-two sulfonamides in edible tissues: Investigation of new metabolites and their potential toxicity

International audienceThe extensive and unregulated use of antibacterial drugs in animal farms in Lebanon can lead to detrimental consequences for the public health. To monitor the levels of sulfonamides and their metabolites in farms in Lebanon, a total of 304 meat samples were collected and analyzed using liquid chromatography coupled to triple quadrupole and hybrid linear ion trap-Orbitrap mass spectrometry following QuEChERS-based extraction. Sulfonamide residues could be detected in forty-six samples, ten of which contained a concentration of sulfaquinoxaline (151.4-1196.7 μg kg-1 in chicken samples) and sulfadiazine (109.8 μg kg-1 in a beef sample) exceeding the European Union-based maximum residue level by 1-12 folds, and thus were unfit for human consumption. Several acetylated, hydroxylated, and/or sulfated metabolites were identified, some of which were not previously detected in edible tissues. Most identified metabolites exhibited potential toxicity equivalent or higher than that of the parent molecule as estimated by in silico tests

Selenium metabolomics in yeast using complementary reversed-phase/hydrophilic ion interaction (HILIC) liquid chromatography-electrospray hybrid quadrupole trap/Orbitrap mass spectrometry

International audienceA high efficiency chromatographic separation on a porous graphitic carbon stationary phase was developed for a large-scale separation of selenium metabolites in Se-rich yeast prior to their identification by electrospray hybrid quadrupole trap/Orbitrap mass spectrometry (Orbitrap MSn). The reversed-phase (RP) separation mode offered distinctly higher separation efficiency than the hydrophilic ion interaction (HILIC) mode. The latter was nevertheless complementary and useful to validate the detection of several compounds. The method allowed the detection of 64 metabolites including 30 SeSe or SeS conjugates (3 triple S/Se/S ones) and 14 selenoethers. 21 previously unreported metabolites were detected on the basis of the selenium isotopic pattern usually matched with the sub-ppm mass accuracy. 9 of these metabolites were subsequently identified using the multi-stage high mass accuracy (<5ppm) mass spectrometry. The identified metabolites (and their groups) were quantified on-line by ICP-MS fitted with a frequency-matching generator allowing a quasi-uniform response over the large (20-90%) acetonitrile mobile phase concentration range. The morphology of HPLC-ICP-MS chromatograms was remarkably similar to that of HPLC multi-ion extracted ESI-MS chromatograms. The detection limits obtained by ICP MS and ESI MS were 1 and 2ppb, respectively

Study of the Size Distribution of Sulfur, Vanadium, and Nickel Compounds in Four Crude Oils and Their Distillation Cuts by Gel Permeation Chromatography Inductively Coupled Plasma High-Resolution Mass Spectrometry

International audienceThe size distribution of sulfur, vanadium, and nickel was determined for four crude oils and their distillation cuts using gel permeation chromatography (GPC) coupled to inductively coupled plasma high-resolution mass spectrometry (ICP HR MS). The results show a trimodal distribution of vanadium and nickel compounds in the crude oils, the atmospheric residues, and the vacuum residues and, for sulfur compounds, either a mono- or bimodal distribution depending upon the distillation cut considered. A correlation exists between the sulfur fraction retention times and the temperature cuts of the distillation for a temperature below 560 degrees C and also between the viscosity of the crude oils and the proportion of trapped sulfur compounds in a higher boiling temperature fraction. The thermic treatment applied for the distillation increases the aggregation of low- and medium-molecular-weight compounds of vanadium and nickel into higher molecular weight aggregates between the crude oil on the one hand and the atmospheric residue and vacuum residue on the other hand, especially when the crude oil has a high total sulfur content

Development of multi-residue routine analysis of 80 pesticides in honeys, honeybees and pollens

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In vivo identification of potential uranium protein targets in zebrafish ovaries after chronic waterborne exposure

International audienceEcotoxicological studies have indicated the reprotoxicity of uranium (U) in zebrafish, but its molecular mechanisms remain unclear. Due to the non-covalent nature of U-protein complexes, canonical proteomics approaches are often not relevant as they usually use denaturating reagents or solvents. In this study, non-denaturating (ND) methods were used to obtain insight into the nature of U potential targets in ovaries of reproduced and non-reproduced zebrafish after 20 days of exposure to an environmentally relevant U concentration (20 μg L(-1)). After the ND sample preparation, 1-dimensional (SEC) and 2-dimensional (OGE × SEC) separations followed by ICP-sector-field MS measurements (U, P, Fe, Cu, and Zn) enabled the determination of chemical characteristics (MW, pI) of the metal-protein complexes. Phosphorus and U coelution confirmed the affinity of U for P-containing proteins. In addition, 2D separation allowed the discrimination of Fe-metalloproteins as potential U targets. Finally, 20 protein candidates for U complexation were identified after tryptic digestion conditions by LC-ESI FT MS and a database search. Potential U targets were mainly involved in three biological processes: oxidative stress regulation (SOD, GST), cytoskeleton structure (actin) and embryo early development (vtg, initiation factor)

Contribution of microbial activity to formation of organically bound chlorine during batch incubation of forest soil using 37Cl as a tracer

cited By 0International audienceChloride is often considered as the main chlorine form in soils. However, recent studies show that chlorine is mostly present in soils as naturally produced organically bound molecules. The relative contribution of biotic, including microbial, and abiotic processes to formation of organically bound chlorine remains poorly understood. We performed a37Cl spiking batch experiment with a forest soil incubated under abiotic and biotic conditions over two time periods to simultaneously monitor the formation of organically bound chlorine from natural and tracer chlorine. To compare biotic and abiotic conditions without biased effect of sterilization technique for abiotic control, the soil was irradiated and reinoculated or not with soil microflora. Fifteen days after microbial inoculation, the natural non-extractable organic chlorine content in the inoculated soil was significantly higher than in the sterile soil, showing that microbial activity contributed to formation of organically bound chlorine. However, no significant difference was noted between the two incubation periods. The same trend was noted for tracer chlorine, yet without a significant difference. The present study shows that chlorination is mediated by microbial activity, but there is also some indication of abiotic formation of organically bound chlorine, with a non-extractable organic tracer chlorine formation of about 6% just after spiking in abiotic conditions. © 2016 Elsevier Lt