Stefania Giannarelli

GC-MS characterization of paint varnishes

Abstract This paper presents an analytical procedure based on gas chromatography separation and mass spectrometric identification, which allows the determination of natural resins, waxes and lipids in the same microsample (

Comparative determination of some phytohormones in wild-type and genetically modified plants by gas chromatography–mass spectrometry and high-performance liquid chromatography–tandem mass spectrometry

The analytical performances of two optimized analytical methodologies used for the determination of auxins, cytokinins, and abscisic acid in plant samples were critically compared. Phytohormones were extracted from Nicotiana glauca samples using a modified Bieleski solvent and determined both by gas chromatography-mass spectrometry (GC-MS), after derivatization with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), and by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) on the Bieleski extract without any further treatment. HPLC-MS/MS gave better results in terms of higher coefficients of determination of the calibration curves, higher and more reproducible recoveries, lower limits of detection, faster sample preparation, and higher sample throughput. Thus, two sets of N. glauca and N. langsdorffii samples, both wild-type and genetically modified by inserting the glucocorticoid receptor (GR) gene encoding for the rat glucocorticoid receptor, were first characterized by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis and then analyzed by HPLC-MS/MS. Significant differences in the phytohormone content between the two sample sets were found and are very important in terms of understanding the mechanisms and effects on growth processes and the development of transgenic plants.

Polychlorobiphenyls and polycyclic aromatic hydrocarbons in the sea-surface micro-layer and the water column at Gerlache Inlet, Antarctica

The enrichment of PCBs (polychlorobiphenyls) and PAHs (polycyclic aromatic hydrocarbons) in the sea-surface micro-layer and depth profile of these pollutants in the water column were investigated at Gerlache Inlet, Terra Nova Bay, Antarctica. Depth profile samplings were repeated three times during the Antarctic summer (from November to February). PCBs and PAHs showed a concentration range in the water column of 30-120 pg l(-1) and 150-400 pg l(-1), respectively, and these values were very much dependent on the suspended matter content. A nearly two-fold decrease in the pollutant concentration was also observed in the depth profile obtained in February, i.e. late summer, which might be correlated both with the high content of suspended matter and the reduction of the pollutant input. Moreover, isomer ratios of PAHs, such as LMW/HMW and PHE/ANT, highlight that the main PAH source might be petrogenic in nature, whereas the pyrolytic source seems to be less important. Sea surface micro-layer (SML) and sub-surface sea water (SSW) samples were simultaneously collected in the same site by a remote controlled rotating drum-based sampling system, a prototype named MUMS (Multi-User Micro-layer Sampler). Sea surface micro-layer samples showed a total content of PCBs and PAHs in the range 400-450 pg l(-1) and 2000-3000 pg l(-1), respectively, whereas the mean content of the sub-surface sea water samples was 48 pg l(-1) and 325 pg l(-1), respectively. The mean enrichment factors of PCBs and PAHs in sea-surface micro-layer were about 10 and 7, respectively. The surface excess concentrations of PCBs and PAHs were about 35 000 and 200 000, respectively. A fairly good correlation was observed between the concentration of pollutants and water solubility. Based on the assumption that POPs are confined in a very thin top layer of the SML about 0.01-0.001 microm thick, namely the sea-surface nano-layer, and also on an estimated thickness of the sampled sea-surface layer of about 100 microm, an enrichment factor of 10(5)-10(6) for the sea-surface nano-layer was calculated. Such a very high concentration increase was related to the two-fold increase of PAH concentration observed in the underlying 20 cm of the water column in late summer.

Response to metal stress of Nicotiana langsdorffii plants wild-type and transgenic for the rat glucocorticoid receptor gene

Recently our findings have shown that the integration of the gene coding for the rat gluco-corticoid receptor (GR receptor) in Nicotiana langsdorffii plants induced morphophysiological effects in transgenic plants through the modification of their hormonal pattern. Phytohormones play a key role in plant responses to many different biotic and abiotic stresses since a modified hormonal profile up-regulates the activation of secondary metabolites involved in the response to stress. In this work transgenic GR plants and isogenic wild type genotypes were exposed to metal stress by treating them with 30ppm cadmium(II) or 50ppm chromium(VI). Hormonal patterns along with changes in key response related metabolites were then monitored and compared. Heavy metal up-take was found to be lower in the GR plants. The transgenic plants exhibited higher values of S-abscisic acid (S-ABA) and 3-indole acetic acid (IAA), salicylic acid and total polyphenols, chlorogenic acid and antiradical activity, compared to the untransformed wild type plants. Both Cd and Cr treatments led to an increase in hormone concentrations and secondary metabolites only in wild type plants. Analysis of the results suggests that the stress responses due to changes in the plants hormonal system may derive from the interaction between the GR receptor and phytosteroids, which are known to play a key role in plant physiology and development.

Impact of Protein Concentration on the Determination of Thiolic Groups of Ovalbumin: A Size Exclusion Chromatography−Chemical Vapor Generation−Atomic Fluorescence Spectrometry Study via Mercury Labeling

We optimized a hyphenated system based on size exclusion chromatography coupled to a microwave/UV mercury oxidation system and an atomic fluorescence detector (SEC-CVG-AFS) for the online oxidation of free and protein-complexed p-hydroxymercuribenzoic acid (pHMB) without the employment of chemical oxidizing agents. This system has been applied to the study of labeling of thiolic groups of native ovalbumin (OVA) as a function of protein concentration. We found that the protein concentration strongly affects the species distribution of OVA, the number of thiolic groups titrated in each species, and thus, the accuracy in the determination of the total number of thiolic groups. The amount of titrated sulfhydryl groups in the protein concentration range investigated (5-100 μmol L(-1)) varied from 2.40 ± 0.01 to 1.85 ± 0.05 for the monomeric form of OVA and from 4.63 ± 0.01 to 5.63 ± 0.05 for the total OVA, which represents more than four theoretical number of reduced Cys. This information is important from the analytical point of view because it suggests that, unless to operate with diluted concentration of protein, the number of titrated thiolic groups results from both the aspecific interaction of the probe with aggregates species and to the specific bond of the probe with the accessible -SH groups.

Electrochemical properties of three dicarboximide-type pesticides : Vinclozoline, iprodione and procymidone

Abstract The reduction mechanism of vinclozoline, 3-(3,5-dichlorophenyl)-5-methyl-5-vinyl-1,3-oxazolidine-2,4-dione, iprodione, 3-(3,5-dichlorophenyl)- N -(1-methylethyl)-2,4-dioxo-1-imidazolidinecarboxamide, and procymidone, 3-(3,5-dichlorophenyl)-1,5-dimethyl-3-azabicyclo[3.1.0]hexane-2,4-dione, was studied in acetonitrile by electrochemical methods combined with GC/MS identification of products. Irreversible reduction was observed at about −2.2 V. The electron transfer reaction was coupled with subsequent chemical reactions yielding several final products. The main decomposition pathways included the elimination of the hetero-ring (producing chloroanilines and most likely diketones) and the cleavage of one or both chlorine atoms. Vinclozoline also yielded compounds that derive from the reductive elimination of the OCO fragment (carbon dioxide) from the heterocyclic ring.

Electrochemical impedance study of reduction kinetics of the pesticide vinclozoline

Abstract The reduction of vinclozoline, 3-(3,5-dichlorophenyl)-5-methyl-5-vinyl-1,3-oxazolidine-2,4-dione, was studied in acetonitrile by electrochemical impedance and by electrolysis combined with GC/MS identification of products. The electron transfer reaction was coupled with subsequent chemical reactions yielding two final products at −2.35 V. The main decomposition pathways included the elimination of the hetero-ring, which produced chloroaniline, whereas the cleavage of one chlorine atom was a much slower process. The kinetic parameters of both chemical processes correlated reasonably well with the observed yield of dichloroaniline and dechlorovinclozoline.

Enrichment, isolation and biodegradation potential of psychrotolerant polychlorinated-biphenyl degrading bacteria from the Kongsfjorden (Svalbard Islands, High Arctic Norway)☆

Persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), have been detected in abiotic Arctic matrices: surface sediments and seawater from coastal areas in the Kongsfjorden were collected and analyzed. Levels of PCBs varied depending on the sampling site. Total PCB concentrations were between 11.63 (site C2W) and 27.69pgl-1 (site AW). These levels were comparable to those reported previously in lake sediments from the northern Svalbard. The occurrence and biodegradation potential of cold-adapted PCB-oxidizing bacteria in seawater and sediment along the fjord was also evaluated. After enrichment with biphenyl, 246 isolates were obtained with 45 of them that were able to grow in the presence of the PCB mixture Aroclor 1242, as the sole carbon source. The catabolic gene bphA was harbored by 17 isolates with affiliates to the genera Algoriphagus, Devosia and Salinibacterium that have been never reported as able to utilize PCBs, thus deserving further investigation. The total removal of Aroclor 1242 and selected PCB congeners was evaluated at 4 and 15°C for eight bphA-harboring isolates and Gelidibacter sp. DS-10. With few exceptions, tested strains showed greater efficiency at 15 than at 4°C. Isolates were able to reduce most chromatographic peaks by >50%, with some di- and trichlorobiphenyls that were quite totally removed (>90%).

Monitoring of depth distribution of trace elements by GDMS

Abstract The depth distribution of B and Li have been studied in ZrO 2 layers by GDMS. Zr alloy has been corroded to ZrO 2 in an autoclave in solutions containing Li and B. Samples were collected at different reaction times and analyzed. The GDMS crater depth and the sputter rate could be determined by profilometry for the discharge conditions used. In the analyzed samples three zones could be identified: oxide, interface and zircaloy. The concentration of Li and B was followed in each of the three zones.

The Effect of Seasonal Pack Ice Melting on the Sea Water Polychlorobiphenyl Contents at Gerlache Inlet and Wood Bay (Ross Sea - Antarctica)

Abstract The effect of seasonal formation/melting process of pack ice on the PCB level of sea water at Gerlache Inlet and Wood Bay (Ross Sea, Antarctica) was investigated during four Italian expeditions, i.e. 1988–89, 1990–91, 1991–92, and 1993–94. Surface sea water samples from Gerlache Inlet and Wood Bay before pack ice melting showed a typical total PCB concentration of 133 pg/l and 120 pg/l, respectively, which increased by a factor of about 1.3 in both sampling sites during pack ice melting. This effect was attributed to the transfer of PCBs contained in the pack ice to sea water, and salinity was used as a tracer to verify this hypothesis. In this respect, pack ice and sea water samples were collected during the 1993–94 Italian expedition, and both salinity (S) and total PCB content were measured. A fairly good agreement was observed between the experimental PCB concentration and the value calculated by the dilution model which was applied to the mixing process between sea and pack ice melting water...