Bismuth Modified Gold Microelectrode for Pb(II) Determination in Wine Using Alkaline Medium

Electrodeposition of bismuth on gold microelectrodes for determination of Pb(II) by square wave anodic stripping voltammetry (SWASV) was accomplished by an in situ procedure in alkaline solution. A linear calibration plot for Pb(II) in the concentration range 40 to 6700 nmol L(-1) (r=0.998) was obtained, the detection limit was found to be 12.5 nmol L(-1) (S/N = 3) and the relative standard deviation in Solutions containing 1 mu mol L(-1) Pb(II) was 4% (n = 12). The analytical performance of the proposed sensor wits tested by measuring the Pb(II) concentration in a wine sample. The result Was in good agreement with the one obtained by GFAAS.

Sediment grain size distribution and heavy metals determination in a dam on the Parana River at Ilha Solteira, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Determination of the photoinduced birefringence and of the refractive index by Brewster method of epoxy resin doped with CdS

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Oxidative stress biomarkers and aggressive behavior in fish exposed to aquatic cadmium contamination

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Electrochemical Determination of Inorganic Contaminants in Automotive Fuels

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A Simple Method Based on ICP-MS for Estimation of Background Levels of Arsenic, Cadmium, Copper, Manganese, Nickel, Lead, and Selenium in Blood of the Brazilian Population

Throughout the world, biomonitoring has become the standard for assessing exposure of individuals to toxic elements as well as for responding to serious environmental public health problems. However, extensive biomonitoring surveys require rapid and simple analytical methods. Thus, a simple and high-throughput method is proposed for the determination of arsenic (As), cadmium (Cd), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and selenium (Se) in blood samples by using inductively coupled plasma-mass spectrometry (ICP-MS). Prior to analysis, 200 l of blood samples was mixed with 500 l of 10% v/v tetramethylammonium hydroxide (TMAH) solution, incubated for 10 min, and subsequently diluted to 10 ml with a solution containing 0.05% w/v ethylenediamine tetraacetic acid (EDTA) + 0.005% v/v Triton X-100. After that, samples were directly analyzed by ICP-MS (ELAN DRC II). Rhodium was selected as an internal standard with matrix-matching calibration. Method detection limits were 0.08, 0.04, 0.5, 0.09, 0.12, 0.04, and 0.1 g//L for As, Cd, Cu, Mn, Ni, Pb, and Se, respectively. Validation data are provided based on the analysis of blood samples from the trace elements inter-\comparison program operated by the Institut National de Sante Publique du Quebec, Canada. Additional validation was provided by the analysis of human blood samples by the proposed method and by using electrothermal atomic absorption spectrometry (ETAAS). The method was subsequently applied for the estimation of background metal blood values in the Brazilian population. In general, the mean concentrations of As, Cd, Cu, Mn, Ni, Pb, and Se in blood were 1.1, 0.4, 890, 9.6, 2.1, 65.4, and 89.3 g/L, respectively, and are in agreement with other global populations. Influences of age, gender, smoking habits, alcohol consumption, and geographical variation on the values were also considered. Smoking habits influenced the levels of Cd in blood. The levels of Cu, Mn, and Pb were significantly correlated with gender, whereas Cu and Pb were significantly correlated with age. There were also interesting differences in Mn and Se levels in the population living in the north of Brazil compared to the south.

Evaluation of the mixtures ammonium phosphate/magnesium nitrate and palladium nitrate/magnesium nitrate as modifiers for simultaneous determination of Cd, Cr, Ni and Pb in mineral water by GFAAS

A method is described for the simultaneous determination of Cd, Cr, Ni and Pb in mineral water samples by graphite furnace atomic absorption spectrometry with a transversely heated graphite atomizer (THGA) and a longitudinal Zeeman-effect background correction system. The electrothermal behavior of analytes during pyrolysis and atomization steps was studied without modifier, in presence of 5 μg Pd and 3 μg Mg(NO3)2 and in presence of 50 μg NH4H2PO4 and 3 μg Mg(NO3)2. A volume of 20 μL of a 0.028 mol L -1 HNO3 solution containing 50 μg L-1 Ni and Pb, 10 μg L-1 Cr and 5 μg L-1 Cd was dispensed into the graphite tube at 20°C. The mixture palladium/magnesium was selected as the optimum modifier. The pyrolysis and atomization temperatures were fixed at 1000°C and 2300°C, respectively. The characteristic masses were calculated as 2.2 pg Cd, 10 pg Cr, 42 pg Ni and 66 pg Pb and the lifetime of the graphite tube was around 600 firings. Limits of detection based on integrated absorbance were 0.02 μg L-1Cd, 0.94 μg L-1 Cr, 0.45 μg L-1 Ni and 0.75 μg L-1 Pb, which exceeded the requirements of Brazilian Food Regulation that establish the maximum permissible level for Cd, Cr, Ni and Pb at 3 μg L-1, 50 μg L-1, 20 μg L-1 and 10 μg L-1, respectively. The recoveries of Cd, Cr, Ni and Pb added to mineral water samples varied within the 93-108%, 96-104%, 87-101% and 98-108% ranges, respectively. Results of analysis of standard reference materials (National Institute of Standards and Technology: 1640-Trace Elements in Natural Water; 1643d-Trace Elements in Water) were in agreement with certified values at the 95% confidence level.

Simultaneous determination of Cd and Pb in antibiotics used in sugar-cane fermentation process by GFAAS

A method has been developed for the simultaneous determination of Cd and Pb in antibiotics used in sugar-cane fermentation by GFAAS. The integrated platform of transversely heated graphite atomizer was treated with tungsten to form a coating of tungsten carbide. Six samples of commercial solid antibiotics were analyzed by injecting 20 μL of digested samples into the pretreated graphite platform with co-injection of 5 μL of 1000 mg L-1 Pd as chemical modifier. Samples were mineralized in a closed-vessel microwave-assisted acid-digestion system using nitric acid plus hydrogen peroxide. The pyrolysis and atomization temperatures of the heating program of the atomizer were selected as 600°C and 2200°C, respectively. The calculated characteristic mass for Cd and Pb was 1.6 pg and 42 pg, respectively. Limits of detection (LOD) based on integrated absorbance were 0.02 μg L -1 Cd and 0.7 μg L-1 Pb and the relative standard deviations (n = 10) for Cd and Pb were 5.7% and 8.0%, respectively. The recoveries of Cd and Pb added to the digested samples varied from 91% to 125% (Cd) and 80% to 112% (Pb).

Voltammetric Study of a Cubic Silsesquioxane Organically Modified with Imidazole and their Subsequent Reaction with Cadmium and Hexacyanoferrate (III)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A simple method based on ICP-MS for estimation of background levels of arsenic, cadmium, copper, manganese, nickel, lead, and selenium in blood of the Brazillian population

Throughout the world, biomonitoring has become the standard for assessing exposure of individuals to toxic elements as well as for responding to serious environmental public health problems. However, extensive biomonitoring surveys require rapid and simple analytical methods. Thus, a simple and high-throughput method is proposed for the determination of arsenic (As), cadmium (Cd), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and selenium (Se) in blood samples by using inductively coupled plasma–mass spectrometry (ICPMS). Prior to analysis, 200 ml of blood samples was mixed with 500 ml of 10% v/v tetramethylammonium hydroxide (TMAH) solution, incubated for 10 min, and subsequently diluted to 10 ml with a solution containing 0.05% w/v ethylenediamine tetraacetic acid (EDTA) + 0.005% v/v Triton X-100. After that, samples were directly analyzed by ICP-MS (ELAN DRC II). Rhodium was selected as an internal standard with matrix-matching calibration. Method detection limits were 0.08, 0.04, 0.5, 0.09, 0.12, 0.04, and 0.1 mg//L for As, Cd, Cu, Mn, Ni, Pb, and Se, respectively. Validation data are provided based on the analysis of blood samples from the trace elements inter-\comparison program operated by the Institut National de Santé Publique du Quebec, Canada. Additional validation was provided by the analysis of human blood samples by the proposed method and by using electrothermal atomic absorption spectrometry (ETAAS). The method was subsequently applied for the estimation of background metal blood values in the Brazilian population. In general, the mean concentrations of As, Cd, Cu, Mn, Ni, Pb, and Se in blood were 1.1, 0.4, 890, 9.6, 2.1, 65.4, and 89.3 mg/L, respectively, and are in agreement with other global populations. Influences of age, gender, smoking habits, alcohol consumption, and geographical variation on the values were also considered. Smoking habits influenced the levels of Cd in blood. The levels of Cu, Mn, and Pb were significantly correlated with gender, whereas Cu and Pb were significantly correlated with age. There were also interesting differences in Mn and Se levels in the population living in the north of Brazil compared to the south.

An Alternative Method for the Simultaneous Determination of Copper and Lead for Quality Control of Sugar Cane Spirit using a Nanotube-Based Sensor

The development of an electroanalytical method for simultaneous determination of copper and lead ions in sugar cane spirit (cachaca) using carbon paste electrode modified with ascorbic acid and carbon nanotubes (CPE-AaCNT) is described. Squarewave voltammetry (SWV) with anodic stripping was employed, and this technique was optimized with respect to the following parameters: frequency (50 Hz), amplitude (100 mV) and scan increment (9 mV). The analytical curves were linear in the range from 0.0900 to 7.00 mg L-1 for lead and copper. The limits of detection were 48.5 and 23.9 mu g L-1 for lead and copper, respectively. The developed method was applied to the simultaneous determination of copper and lead in five commercial samples of sugar cane spirit. The results were in good agreement with those obtained by F AAS/GF AAS (flame atomic absorption spectrometry/graphite furnace atomic absorption spectrometry) and showed that CPE-AaCNT can be successfully employed in the simultaneous determination of these metals in real sugar cane spirit samples.

Cadmium and Chromium Toxicity to Pseudokirchneriella subcapitata and Microcystis aeruginosa

The toxicity of cadmium and chromium to Pseudokirchneriella subcapitata and Microcystis aeruginosa was evaluated through algal growth rate during 96h exposure bioassays. Free metal ion concentrations were obtained using MINEQL(+) 4.61 and used for IC50 determination. Metal accumulations by the microorganisms were determined and they were found to be dependent on the concentration of Cd2+ and Cr6+. IC50 for P. subcapitata were 0.60 mu mol L-1 free Cd2+ and 20 mu mol L-1 free Cr6+, while the IC50 values for M. aeruginosa were 0.01 mu mol L-1 Cd2+ and 11.07 mu mol L-1 Cr6+. P. subcapitata accumulated higher metal concentrations (0.001 - 0.05 mu mol Cd mg(-1) dry wt. and 0.001 - 0.04 mu mol Cr mg(-1) dry wt) than the cyanobacteria (0.001 - 0.01 mu mol Cd mg(-1) dry wt and 0.001 - 0.02 mu mol Cr mg(-1) dry wt). Cadmium was more toxic than chromium to both the microorganisms.

On Site Stripping Voltammetric Determination of Zn(II), Cd(II) and Pb(II) in Water Samples of the Cananeia-Iguape Estuarine-Lagoon Complex in Sao Paulo State, Brazil

Estuarine systems play an important role in the retention of toxic trace elements owing to the affinity of these elements with particles dissolved in water. This work presents the use of a voltammetric sensor to monitor heavy metal (Zn (II), Cd(II) and Pb (II)) concentrations in the Cananeia-Iguape Estuarine-Lagoon region (Sao Paulo State, Brazil). Lower concentrations were found in the Southern estuarine system (Cananeia City) and increased concentrations observed in the Northern sector (Iguape City) were promoted by anthropogenic activities, with particular influence from the historical introduction of mining wastes and inputs from agricultural, industrial and domestic effluents. The proposed method is reliable, inexpensive and fast, can simultaneously provide information on the concentration of these metallic ions and can be easily used for field measurements aboard oceanographic ships.

On site stripping voltammetric determination of Zn(II), Cd(II) and Pb(II) in water samples of the Cananéia-Iguape Estuarine-Lagoon complex in São Paulo state, Brazil

Estuarine systems play an important role in the retention of toxic trace elements owing to the affinity of these elements with particles dissolved in water. This work presents the use of a voltammetric sensor to monitor heavy metal (Zn (II), Cd(II) and Pb (II)) concentrations in the Cananéia-Iguape Estuarine-Lagoon region (São Paulo State, Brazil). Lower concentrations were found in the Southern estuarine system (Cananéia City) and increased concentrations observed in the Northern sector (Iguape City) were promoted by anthropogenic activities, with particular influence from the historical introduction of mining wastes and inputs from agricultural, industrial and domestic effluents. The proposed method is reliable, inexpensive and fast, can simultaneously provide information on the concentration of these metallic ions and can be easily used for field measurements aboard oceanographic ships.

Determination of preventive maintenance lead time using hybrid analysis

The time for conducting Preventive Maintenance (PM) on an asset is often determined using a predefined alarm limit based on trends of a hazard function. In this paper, the authors propose using both hazard and reliability functions to improve the accuracy of the prediction particularly when the failure characteristic of the asset whole life is modelled using different failure distributions for the different stages of the life of the asset. The proposed method is validated using simulations and case studies.