Simulation of a surface spill of different diesel/biodiesel mixtures in an ultisol, using natural attenuation and bioaugmentation/biostimulation.

Accidents caused by leaks and/or spills on soils need to be addressed. Natural attenuation, biostimulation and bioaugmentation can be useful bioremediation strategies for decontamination processes in soils of diesel/biodiesel mixtures. The purpose of this study was to evaluate the degradation rate of the different fuels (B0, B20 and B100) in an ultisol under natural attenuation and biostimulation/bioaugmentation during 60 days of incubation in a controlled microcosm simulating a surface spill over soil. The degradation of different diesel/biodiesel mixtures was monitored for up to 60 days by dehydrogenase activity, respirometry by CO2 release, the most probable number of heterotrophic and degrading microorganism and gas chromatography. The bacterial inoculum employed for biostimulation/bioaugmentation strategy consisted of Bacillus megaterium, Bacillus pumilus, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia. The two bioremediation strategies have showed great degradation rates. The natural attenuation was effective for B0 and B20 treatments. The addition of the bacterial consortium and macronutrients contributed to the increased degradation of pure biodiesel in relation to natural attenuation, with higher rates for CO2 release, enzymatic and degrading activity. It is suggested that the bacterial consortium has proven effective for presenting significant values for such parameters until the end of the 60-day incubation period.

Chemical pretreatment of Arundo donax L. for second-generation ethanol production

Background: Pretreatment of lignocellulosic biomass is essential for using it as a raw material for chemical and biofuel production. This study evaluates the effects of variables in the chemical pretreatment of the Arundo biomass on the glucose and xylose concentrations in the final enzymatic hydrolysate. Three pretreatments were tested: acid pretreatment, acid pretreatment followed by alkaline pretreatment, and alkaline pretreatment. Results: The amounts of glucose and xylose released by the enzymatic hydrolysis of the Arundo biomass obtained from acid pretreatment ranged from 6.2 to 19.1 g/L and 1.8 to 3.1 g/L, respectively. The addition of alkaline pretreatment led to a higher yield from the enzymatic hydrolysis, with the average glucose concentration 3.5 times that obtained after biomass hydrolysis with an acid pretreatment exclusively. The use of an alkaline pretreatment alone resulted in glucose and xylose concentrations similar to those obtained in the two-step pretreatment: acid pretreatment followed by alkaline pretreatment. There was no significant difference in 5-hydroxymethylfurfural, furfural, or acetic acid concentrations among the pretreatments. Conclusion: Alkaline pretreatment was essential for obtaining high concentrations of glucose and xylose. The application of an alkaline pretreatment alone resulted in high glucose and xylose concentrations. This result is very significant as it allows a cost reduction by eliminating one step.

PAHs in corn grains submitted to drying with firewood.

Grain drying using firewood as fuel for air heating, with direct fire, is still widely used in Brazil. The combustion of organic material, such as wood, can generate polycyclic aromatic hydrocarbons (PAHs) which are known to have carcinogenic potential. In the present work corn grain drying was carried out at three drying air temperatures: 60°C, 60/80°C and 80°C. Following the drying process, the presence and quantification of PAH in the corn grains was investigated. After extracting the PAHs of the matrix, the material was subjected to analysis by gas chromatography with mass detector. he results showed the presence of seven compounds: fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene and chrysene.

Structural elucidation of sulfaquinoxaline metabolism products and their occurrence in biological samples using high-resolution Orbitrap mass spectrometry.

Four previously unreported metabolism products of sulfaquinoxaline (SQX), a widely used veterinary medicine, were isolated and analyzed using liquid chromatography coupled to high-resolution Orbitrap mass spectrometry. Metabolites were structurally elucidated, and a fragmentation pathway was proposed. The combination of high-resolution MS(2) spectra, linear ion trap MS(2), in-source collision-induced dissociation (CID) fragmentation, and photolysis were used to analyze SQX and its metabolites. All metabolism products identified showed a similar fragmentation pattern to that of the original drug. Differential product ions were produced at m/z 162 and 253 which contain the radical moiety with more 16 Da units than sulfaquinoxaline. This occurs by a hydroxyl attachment to the quinoxaline moiety. With the exception of two low-intensity compounds, all the mass errors were below 5.0 ppm. The distribution of these metabolites in some animal species are also presented and discussed.

Scope extension validation protocol: inclusion of analytes and matrices in an LC-MS/MS sulfonamide residues method.

Validation is a required process for analytical methods. However, scope extension, i.e. inclusion of more analytes, other matrices and/or minor changes in extraction procedures, can be achieved without a full validation protocol, which requires time and is laborious to the laboratory. This paper presents a simple and rugged protocol for validation in the case of extension of scope. Based on a previously reported method for analysis of sulfonamide residues using LC-MS/MS, inclusion of more analytes, metabolites, matrices and optimisation for the extraction procedure are presented in detail. Initially, the method was applied only to liver samples. In this work, milk, eggs and feed were also added to the scope. Several case-specific validation protocols are proposed for extension of scope.

Influência do sistema de produção e do armazenamento refrigerado nas características físico-químicas e no desenvolvimento de compostos voláteis em morangos / Influence of planting system and cold storage on the physical-chemistries characteristicsand volatile compounds development in strawberries

Durante o armazenamento, pode ocorrer a perda de compostos voláteis responsáveis pelo aroma e o aumento de compostos indesejáveis, o que ocasiona a perda de qualidade do morango, reduzindo a vida de prateleira e levando à rejeição do produto pelos consumidores. Neste trabalho, foi avaliada a influência do sistema de produção (convencional e orgânico) e do período de armazenamento (0, 2, 5, 8 dias) nas características físicas e químicas (CFQ) e nos compostos voláteis (CV) de morango das cultivares 'Camarosa' e 'Camino Real', utilizando morangos de pomar comercial da região de Pelotas/RS. Os frutos foram colhidos em estádio de maturação comercial e com boa aparência. O planejamento experimental foi casualizado, em triplicata de 15 frutos. Os morangos foram armazenados a T de 1°C, com 90-95% umidade relativa (UR). Foram avaliadas a perda de massa, a coloração instrumental [L*, a*, b* e ângulo hue (H)] , a firmeza, os sólidos solúveis (SS), a acidez titulável (AT), a relação SS/AT, pH e os teores de CV. Os resultados foram submetidos à análise de variância e as diferenças significativas determinadas pelo teste de Tukey (P<0,05). Os resultados revelaram que pH, SS, relação SS/AT, podridões e perda de massa aumentaram durante o armazenamento. A firmeza se manteve irregular e a AT e H diminuíram significativamente. Os teores de CV aumentaram com exceção do acetato de metila (AM). O etanol (Et), o acetaldeído (AA) e o acetato de etila (AE) correlacionaram-se positivamente com o teor de podridões para a cultivar 'Camino Real' do cultivo orgânico. De modo geral o AM correlacionou-se inversamente com o teor de podridões, exceto para a cultivar 'Camino Real' do cultivo convencional. Os morangos de ambas as cultivares podem ser armazenados por cinco dias com qualidade, independente do sistema de produção.

During the storage a loss of volatile compounds responsible for the aroma and an increase of undesirable compounds can occur leading to a decrease in the strawberry quality, a reduction of the shelf life and product rejection by the consumers. In the present work the influence of the planting system (conventional and organic) and the storage period (0, 2, 5 and 8 days) upon physical and chemical characteristics (FCC) as well as on strawberry volatile compounds (VC) in the cultivars 'Camarosa' and 'Camino Real' were evaluated using strawberries from a commercial orchard from Pelotas/RS. The fruits were harvested in a stage of commercial maturation and sound appearance. The experimental planning was randomized, in triplicate of fifteen fruits. The strawberries were stored at 1°C and 90-95% of relative humidity (RH). The mass loss, the instrumental color [L*, a*, b* and hue angle (H)], the firmness, the soluble solids (SS), the titratable acidity (TA), the SS/TA ratio, the pH and VC content were determined. The results were analyzed by analysis of variance and significant differences were determined using Tukey's test (P<0.05). The results show that pH, SS, relation SS/TA, decay and mass loss have increased during storage. The firmness varied irregularly and TA and H decreased significantly. The values of VC increased with the exception of methyl acetate (MA). Ethanol (Et), acetaldehyde (AA) and ethyl acetate (EA) correlated positively with decay for organic cultivated 'Camino Real'. In a general way, the MA correlated inversely with decay with the exception of conventional cultivated 'Camino Real'. Strawberries from both cultures can be stored for five days without loosing quality regardless the production system.

Bioprospection and selection of bacteria isolated from environments contaminated with petrochemical residues for application in bioremediation.

The use of microorganisms with hydrocarbon degrading capability and biosurfactant producers have emerged as an alternative for sustainable treatment of environmental passives. In this study 45 bacteria were isolated from samples contaminated with petrochemical residues, from which 21 were obtained from Landfarming soil contaminated with oily sludge, 11 were obtained from petrochemical industry effluents and 13 were originated directly from oily sludge. The metabolization capability of different carbon sources, growth capacity and tolerance, biosurfactant production and enzymes detection were determined. A preliminary selection carried out through the analysis of capability for degrading hydrocarbons showed that 22% of the isolates were able to degrade all carbon sources employed. On the other hand, in 36% of the isolates, the degradation of the oily sludge started within 18-48 h. Those isolates were considered as the most efficient ones. Twenty isolates, identified based on partial sequencing of the 16S rRNA gene, were pre-selected. These isolates showed ability for growing in a medium containing 1% of oily sludge as the sole carbon source, tolerance in a medium containing up to 30% of oily sludge, ability for biosurfactant production, and expression of enzymes involved in degradation of aliphatic and aromatic compounds. Five bacteria, identified as Stenotrophomonas acidaminiphila BB5, Bacillus megaterium BB6, Bacillus cibi, Pseudomonas aeruginosa, and Bacillus cereus BS20 were shown to be promising for use as inoculum in bioremediation processes (bioaugmentation) of areas contaminated with petrochemical residues since they can use oily sludge as the sole carbon source and produce biosurfactants.

Oxidative stress in patients with mucopolysaccharidosis type II before and during enzyme replacement therapy.

Mucopolysaccharidosis type II (MPS II) is a lysosomal storage disorder caused by deficiency of the enzyme iduronate-2-sulfatase, responsible for the degradation of glycosaminoglycans dermatan and heparan sulfate. Once the generation of free radicals is involved in the pathogenesis of many diseases, including some inborn errors of metabolism, the aim of this study was to evaluate blood oxidative stress parameters in MPS II patients, before and during 6 months of enzyme replacement therapy. We found significantly increased levels of malondialdehyde and carbonyl groups in plasma as well as erythrocyte catalase activity in patients before treatment compared to the control group. Plasma sulfhydryl group content and total antioxidant status were significantly reduced before treatment, while superoxide dismutase enzyme was not altered at this time when compared to controls. During enzyme replacement therapy, there was a significant reduction in levels of malondialdehyde when compared to pretreatment. Sulfhydryl groups were significantly increased until three months of treatment in MPS II patients in comparison to pretreatment. There were no significant alterations in plasma total antioxidant status and carbonyl groups as well as in catalase and superoxide dismutase activities during treatment in relation to pretreatment. The results indicate that MPS II patients are subject to lipid and protein oxidative damage and present reduction in non-enzymatic antioxidants, suggesting a possible involvement of free radicals in the pathophysiology of this disease. Also, the results may suggest that enzyme replacement therapy seems to protect against lipid peroxidation and protein damage in these patients.

Biodegradation of commercial gasoline (24% ethanol added) in liquid medium by microorganisms isolated from a landfarming site.

Isolation of soil microorganisms from a landfarming site with a 19-year history of petrochemical residues disposal was carried out. After isolation, the bacteria behavior in mineral medium with 1% commercial gasoline (24% ethanol) was evaluated. Parameters employed for microorganism evaluation and selection of those with the greatest degradation potential were: microbial growth; biosurfactant generation and compound reduction in commercial gasoline. Starting from bacteria that presented the best degradation results, consortiums formed by 4 distinct microorganisms were formed. A microbial growth in the presence of commercial gasoline was observed and, for most of the bacteria, degradations of compounds such as benzene, toluene and xylenes (BTX) as well as biosurfactant production was observed. Ethanol was partially degraded by the bacterial isolates although the data does not allow affirming that it was degraded preferentially to the aromatic hydrocarbons investigated. The analyzed consortiums present an efficiency of 95% to 98% for most of the commercial gasoline compounds and a preferential attack to ethanol under the essay condition was not observed within 72 h.

Simvastatin treatment prevents oxidative damage to DNA in whole blood leukocytes of dyslipidemic type 2 diabetic patients.

Type 2 diabetes (T2D) is associated with increased oxidative stress as indicated by elevated levels of lipid peroxidation and protein oxidation products. Since reactive oxygen species (ROS) can cause damage to biological macromolecules including DNA, this study investigated oxidative damage to DNA using the alkaline (pH > 13) comet assay in peripheral whole blood leukocytes sampled from 15 dyslipidemic T2D patients treated with simvastatin (20 mg/day), 15 dyslipidemic T2D patients not treated with simvastatin, 20 non-dyslipidemic T2D patients, and 20 healthy individuals (controls). Our results showed a greater DNA migration in terms of damage index (DI) (p < 0.01) in the dyslipidemic T2D patients not treated with statin (DI = 67.70 +/- 10.89) when compared to the dyslipidemic T2D patients under statin treatment (DI = 47.56 +/- 7.02), non-dyslipidemic T2D patients (DI = 52.25 +/- 9.14), and controls (DI = 13.20 +/- 6.40). Plasma malondialdehyde (MDA) and C-reactive protein (CRP) levels were also increased and total antioxidant reactivity (TAR) and paraoxonase activity (PON1) decreased in non-dyslipidemic T2D patients and dyslipidemic T2D non-treated with simvastatin. We also found that DI was inversely correlated with TAR (r = -0.61, p < 0.05) and PON1 (r = -0.67, p < 0.01). In addition, there was a significant positive correlation between DI and CRP (r = 0.80, p < 0.01). Our results therefore indicate that simvastatin treatment plays a protective role on oxidative damage to DNA in dyslipidemic T2D patients probably reflecting a general decrease in oxidative stress in these patients.

Apolipoprotein, C-reactive protein and oxidative stress parameters in dyslipidemic type 2 diabetic patients treated or not with simvastatin.

BACKGROUND AND AIMS: Oxidative stress is considered an important factor in the development of diabetic complications that causes a variety of changes such as oxidative modification of membrane lipids, nucleic acids and cellular proteins. Dyslipidemia is frequently associated with diabetes and cardiovascular disease. In this context, the objective of this study was to evaluate oxidative modifications of plasma proteins and lipids in non dyslipidemic type 2 diabetic (T2D) patients, in dyslipidemic T2D patients treated or not with simvastatin and in healthy subjects to investigate whether treatment with low doses of simvastatin plays a protective role on the lipid and protein oxidative damage in these patients. METHODS: We determined oxidative damage of plasma proteins by carbonyl assay and total thiol group determination. We also characterized the membrane damage in terms of lipid peroxidation by measuring malonaldehyde (MDA) in nondyslipidemic T2D patients, dyslipidemic T2D patients treated with simvastatin (20 mg/day), dyslipidemic T2D patients not treated with simvastatin and in healthy age-matched control subjects. RESULTS: Our results showed that dyslipidemic T2D patients not treated with simvastatin had significantly higher plasma protein carbonyl groups and MDA when compared to dyslipidemic T2D patients treated with simvastatin and control group. Thiol concentrations from dyslipidemic T2D patients not treated with simvastatin were significantly lower than treated patients and controls. It was verified that the thiols groups were inversely correlated with apolipoprotein B and positively correlated with apolipoprotein A-I. CONCLUSIONS: These results demonstrated that treatment with low doses of simvastatin can minimize the protein and lipid oxidative damage in dyslipidemic T2D patients.

Biodegradation of tebuconazole by bacteria isolated from contaminated soils.

The objective of this work was to isolate bacteria from soil historically exposed to tebuconazole and to evaluate the biodegradation of this fungicide by them. Tebuconazole is a commonly used systemic fungicide of the triazol group, which inhibits the sterol C-14 alpha-demethylation of 24-methylenedihydrolanosterol, a precursor of ergosterol, a cell membrane component in fungi. Microorganisms were isolated by different methods of soil sampling and the screening of degrading bacteria was performed in bioreactors cultivations, with some isolates showing the ability to degrade up to 42.76 mg L(- 1) of tebuconazole (51% of the initial concentration). These strains were identified by standard biochemical procedures as being Enterobacter sakazakii and Serratia sp. These bacteria present some important characteristics for potential uses on environmental bioremediation, considering that tebucanozale is an extremely recalcitrant chemical.

Blood antioxidant parameters in sickle cell anemia patients in steady state.

Sickle cell anemia (SCA) is a hereditary disorder with higher potential for oxidative damage due to chronic redox imbalance in red cells. We measured antioxidant enzymes including catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD). We also determined oxidative damage of proteins in hemolysate of red blood cells (RBCs) and plasma (carbonyl assay). We characterized the membrane damage in terms of lipid peroxidation by accumulation of malonaldehyde (MDA) by HPLC in 30 healthy controls and 20 SCA patients in steady-state condition. Twenty (9 males/11 females) adult SCA patients and 30 healthy controls were studied. All patients and control subjects had antioxidant (CAT, GPx, SOD, carbonyl and MDA) and hematological parameters done. Our data show that SCA patients had significant higher GPx and SOD activities than healthy controls. Carbonyl assay was noted in plasma but not in hemolysate. An enhanced production of MDA was observed in the serum of SCA patients. Our data support the growing evidence that patients with SCA are subjected to chronic oxidative stress and are able to oxidative damage in biological macromolecules such as proteins and lipids.

Anthracene biodegradation and surface activity by an iron-stimulated Pseudomonas sp.

Iron may enhance polycyclic aromatic hydrocarbons (PAHs) degradation directly by increasing the activity of the enzymes involved in the aerobic biodegradation pathways for hydrocarbons, and indirectly by increasing the PAHs bioavailability due to the stimulation of biosurfactant production. In the present work, the PAH anthracene was used in order to study the effect of different forms and concentrations of iron on its biodegradation and surfactant production by Pseudomonas spp. isolates from a 14-years old petrochemical sludge landfarm site. Among the iron forms, iron nitrate was chosen based on its high solubility and effect on the increase in the growth of the isolate. Iron concentration of 0.1mM was selected as the limit between deficiency and toxicity for isolates growth and anthracene degradation. After 48 days Pseudomonas citronellolis isolate 222A degraded 72% of anthracene related to iron stimulation and surface tension decrease, indicating surfactant production. Pseudomonas aeruginosa isolate 332C was iron-stimulated but did not reduce surface tension while P. aeruginosa isolate 312A exhibited a noniron and surfactant dependence to degrade 72% of anthracene. Isolate 222A showed a direct dependence on iron to stimulate surfactant activity, which probably increased anthracene bioavailability. To our knowledge, this is the first report about the iron effect on anthracene degradation and surfactant production by a Pseudomonas sp. Based on the iron requirement and surfactant activity, the Pseudomonas isolates may be useful for bioremediation of PAHs.

Polycyclic aromatic hydrocarbons in sediments from Rodrigo de Freitas Lagoon in the urban area of Rio de Janeiro, Brasil.

Regular (non-alkylated) polycyclic aromatic hydrocarbons (PAHs) and their alkylated homologues were determined in sediments from Rodrigo de Freitas Lagoon using gas chromatography with mass selective detector (GC-MSD). Concentrations varying from 405 to 11734 ng x g(-1) were found for total PAHs (regular and alkylated homologues). The study showed a pyrogenic and petrogenic contribution, probably due to the incomplete burning of fossil fuels as a result of the intense traffic of boats and motor vehicles added to the anthropogenic activity of several gas stations present in the region of Rodrigo de Freitas Lagoon. According to the National Oceanic and Atmospheric Administration (NOAA) Sediment Quality Guide, PAHs concentration should not exceed 4000 ng x g(-1) (Long et al., 1995) The obtained data present values above the NOAA limit for some sampling points indicating chronic contamination of those sites probably due to anthropogenic activities related to petroleum and its derivatives.

Sodium ferrate (IV) and sodium hypochlorite in disinfection of biologically treated effluents. Ammonium nitrogen protection against THMs and HAAs.

The work described in this paper presents an evaluation of disinfection by-products generation in four different biological treatment plant effluents, making use of sodium hypochlorite and sodium ferrate (IV) at varying concentration and reaction time. Correlations between pH, chemical oxygen demand, total organic carbon, ammonium nitrogen, combined chlorine and trihalomethanes (THMs) and haloacetic acids (HAAs) were carried out. Disinfection by-products generation presented a direct relation with concentration and sodium hypochlorite reaction time. For the highest hypochlorite concentration employed (20 mg L(-1)) and highest reaction time (168 h), the THMs total did not exceed 312.96 microg L(-1), a value that lies below the Brazilian emission standard for treated effluents (1 mg L(-1) of chloroform). The THMs presented an inverse correlation with ammonium nitrogen, when inverse (R(2) = 0.646; P < 0.001) and exponential (R(2) = 0.707; P < 0.001) function were used. As per HAAs this same relation was observed for logarithmic (R(2) = 0.0397 P < 0.001) and exponential (R(2) = 0.508; P < 0.001) functions. The more nitrified the effluent, the bigger the chlorinated disinfection by-product generation. The disinfectant sodium ferrate (IV) does not lead to halogenated by-product formation.

Rapid screening method for determination of PCDDs and PCDFs in fly ashes using GC-ion trap MS/MS based on cellular disruptor extraction.

Identification and quantification of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in fly ashes from incinerator was carried out using capillary gas chromatography/tandem mass spectrometry (GC/MS/MS) with a low resolution ion trap mass spectrometer. Sample extraction was carried out in a cellular disruptor, in Soxhlet and in a conventional ultrasound for comparative purposes. Extraction with cellular disruptor was shown to be comparable to that obtained by the reference Soxhlet extraction, while low recoveries were observed with ultrasound. Hospital incinerator ashes, extracted by cellular disruptor and Soxhlet presented I-TEQ values for polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans of 370 +/- 81 ng g(-1) and 533 +/- 55 ng g(-1), respectively, statistically equivalent according to the t-test.

Evaluation of zirconocene-based silica phases in organochloride pesticides preconcentration.

Silica was chemically modified with zirconocenes, namely Cp(2)ZrCl(2), (MeCp)(2)ZrCl(2), (iBuCp)(2)ZrCl(2) and (nBuCp)(2)ZrCl(2) by grafting. Hybrid silica bearing surface indene groups was synthesized by the sol-gel method, followed by metallation with ZrCl(4)2THF. According to RBS measurements, metal content was 0.2-0.3 wt% Zr/SiO(2) for the grafted systems and 4.5 wt% Zr/SiO(2) for the phase prepared by the sol-gel method. The solid phases were evaluated in the adsorption/preconcentration of organochloride (hexachlorobenzene, lindane, heptachlor, heptachlor epoxide, dieldrin and endrin) pesticides from aqueous solution. For comparative reasons, commercial LC-18 phase was also evaluated. Analyte concentration was monitored by GC-ECD. For the grafted phases, the coordination sphere around the metal center seems not to influence the adsorption/desorption properties of these phases vis-à-vis the studied analytes. Recoveries results for both analytes were comparable to those observed in the case of LC-18 in the case of the phases prepared by the sol-gel method. Experiments using ZrO(2) and ZrO(2)/SiO(2) phases led to lower recovery results.

Adaptative response to enhanced basal oxidative damage in sod mutants from Saccharomyces cerevisiae.

We investigated the adaptative response of S. cerevisiae in sod mutants (sod 1 Delta, sod 2 Delta and sod 1 Deltasod 2 Delta) after H(2)O(2) treatment in the stationary phase. sod 2 Delta and sod 1 Deltasod 2 Delta demonstrated the highest levels of GSH in the control, suggesting that pathways which include GSH protect these double mutants against oxidative stress. In addition, sod 1 Delta and sod 1 Deltasod 2 Delta had higher iron levels than the wild-type, independently of H(2)O(2) stress. Fe levels were increased in sod 2 Delta following H(2)O(2) In addition, the sod 2 Delta mutant was more sensitive to H(2)O(2) treatment than the wild-type. These results suggest that sod 2 Delta sensibility may be associated with *OH production by the Fenton reaction. This increased iron demand in the sod 2 Delta mutant may be a reflection of the cells' efforts to reconstitute proteins that are inactivated in conditions of excess superoxide. MDA levels were assayed by HPLC in these mutants. The highest MDA levels could be observed after 10mM H(2)O(2) treatment in the sod 1 Deltasod 2 Delta double mutant. After treatment with a GSH inhibitor, the MDA level was still higher in the same strain. Thus, both direct and indirect GSH pathways are involved in the protection of lipid membranes and proteins in these mutants and may constitute an adaptative response to enhanced basal oxidative damage produced by superoxide.

Synthesis of zirconocene-based silica phases and evaluation in lindane and heptachlor epoxide adsorption/desorption.

Silica (350 m(2) g(-1)) was chemically modified with Cp2ZrCl2 and (nBuCp)2ZrCl2 by grafting. Hybrid silica bearing surface indene groups was synthesized by the sol-gel method, followed by metallation with ZrCl(4)2THF. The resulting phases were characterized by Rutherford backscattering spectrometry (RBS), 13C and 29Si magic angle spin nuclear magnetic resonance, X-ray photoelectron spectroscopy, and diffuse reflectance infrared Fourier transform spectroscopy. According to RBS measurements, metal content was 0.2- to 0.3-wt% Zr/SiO2 for the grafted systems and 4.5-wt% Zr/SiO2 for the phase prepared by the sol-gel method. The solid phases were evaluated for the adsorption/preconcentration of lindane and heptachlor epoxide from aqueous solution. For comparative reasons, the commercial LC-18 phase was also evaluated. Analyte concentration was monitored by gas chromatography electron capture detection. For the grafted phases, the coordination sphere around the metal center seems not to influence the adsorption/desorption properties of these phases vis-a-vis the studied analytes. In the case of the phases prepared by the sol-gel method, recovery results were comparable to those observed for LC-18. Experiments using ZrO2 and ZrO2/SiO2 phases led to lower recovery results.