Simultaneous determination of Pb and Cd in seafood by ICP OES with on-line pre-concentration by solid phase extraction with amberlite XAD-4 after complex formation with DDTP

An on-line method for Cd and Pb pre-concentration and simultaneous determination in acid digested seafood by inductively coupled plasma optical emission spectrometry (ICP OES) was developed. The on-line pre-concentration was based on the complex formation of the analytes with the ammonium salt of O,O-diethyldithiophosphate (DDTP) and using the Amberlite XAD-4 resin as a solid support in a homemade column. Different conditions of the flow injection system, such as solutions flow rates, nebulizer pressure and eluent concentration were optimized. Three certified reference materials of lobster hepatopancreas, dogfish liver and fish protein, three samples of fish muscle and three samples of shrimp were digested with HNO3, H2O2 and H2SO4 in a microwave system under reflux. DDTP was added in the solutions obtained, and the mixture was injected in the FI system. Calibration curves for Cd and Pb were obtained using the standard solutions in the concentration range 0.05-0.5 µg mL-1 in the digestion medium, submitted to the same pre-concentration procedure. The quantification limits (3.3 x LOD) for 5 min of pre-concentration time were 0.005 mg kg-1 Cd2+ and 0.1 mg kg-1 Pb2+ in the sample of fish or shrimp in natura, considering 1.0 g of the sample in a final volume of 50 mL. The agreement of the obtained concentrations with the certified ones (Student t-test, 95% confidence) and the recoveries of spiked real samples, from 90 to 120%, demonstrated good accuracy. Precision was also adequate, with relative standard deviations from 2 to 13%. The method was accurate, precise and certainly could be applied to the digested samples of different natures.

Fast assessment of mineral constituents in grass by inductively coupled plasma optical emission spectrometry

A method for evaluating inorganic constituents in the grass by ICP OES is proposed. The samples were digested with nitric acid plus hydrogen peroxide in a microwave system. Seventeen samples were collected in the metropolitan area of Curitiba and Castro in the Paraná State, Brazil. The following elements were studied: Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Pb, Sb, Se and Zn. The linear coefficients of the curves were higher than 0.999 and the precision, expressed as the relative standard deviation, which was below 10%, being considered adequate. The accuracy was validated by using the recovery test (recoveries from 80 to 107%) and by the analysis of botanical certified materials. For one sample, two other digestion procedures, using two different mixtures of nitric and hydrochloric acids, produced results in agreement with the adopted procedure. Eleven out of the twenty studied elements could be quantified in real samples. High concentrations of Ca, K, Mg and P, the essential elements for bovines and other animals, were found. The results were evaluated using the principal component analysis that gathered the samples in three groups, according to the areas where the plants were grown.

Biochemical biomarkers and metals in Perna perna mussels from mariculture zones of Santa Catarina, Brazil.

The activity of cholinesterase (ChE), glutathione-S transferase (GST), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PDH) and catalase (CAT) was evaluated in the gill and digestive glands of the Perna perna mussel transplanted to three non-contaminated mariculture zones under the influence of distinct physical-chemical characteristics. Differences among sites for ChE, GST and CAT activities in gill, as well as ChE, GST and G6PDH activity in digestive gland of mussels, were found and possibly related to differences in physicochemical characteristics of the sites and/or biological status of the mussels. Mussels that were transplanted to another, more urbanized site (Ponta do Lessa) with similar physicochemical characteristics to one of the farming sites (Sambaqui), was also chosen to evaluate biomarker responses to pollution. Activities of ChE, GST and GR in the digestive glands and CAT in the gills were higher in the polluted site. GR was the only biomarker to be unaltered in different farming sites, but induced in the pollution site. The trace metal concentrations in the mussels were low and unlikely to cause the changes observed in the biomarker levels. The present study strongly suggests that monitoring programs should compare sites with similar physicochemical characteristics when using a complementary biomarker approach. In addition, the baselines for the biomarkers and metal used in the present study can serve as a reference for the monitoring of these mariculture zones in future monitoring programs employing P. perna.

Simultaneous on-line pre-concentration and determination of trace metals in environmental samples by flow injection combined with inductively coupled plasma mass spectrometry using silica gel modified with niobium(V) oxide.

This work presents the development of an on-line pre-concentration system for simultaneous determination of Cd, Cu, Ni, V, Zn, Co and Pb in aqueous environmental samples and detection by inductively coupled plasma mass spectrometry. The system is based on cationic retention of the analytes onto a mini-column filled with silica gel modified with niobium(V) oxide. The effects of chemicals and flow variables have been investigated. The optimized operating conditions, selected as a compromise between sensitivity and analytical frequency were: sample pH 7.0, sample flow rate of 6.0mL min(-1), eluent flow rate of 2.0mL min(-1), and eluent (HNO(3)) concentration of 2.5mol L(-1). The relative standard deviation (n=7), enrichment factor and linear working range were 0.8-4.5%, 23.3-37.2 and 0.05-25.0microg L(-1), respectively. Limits of detection were between 0.01 and 0.03microg L(-1). The accuracy of the proposed method was checked with certified materials (NASS-4, NASS-5, CASS-4 and SRM 1643e). Values obtained were in accordance with those reported for the certified materials. Recovery was found to be in the range of 90-110% for a suit of water samples with variable matrices (seawater, tap water and ground water) collected in Florianopolis, Brazil.

Determination of lead in sediments and sewage sludge by on-line hydride-generation axial-view inductively-coupled plasma optical-emission spectrometry using slurry sampling.

Among the "traditional" hydride-forming elements, lead is probably the most difficult, and its determination in this form has rarely been reported in the literature. In this paper a simple and rapid method, axial-view inductively-coupled plasma optical-emission spectrometry using on-line hydride generation (HG-ICP-OES) from samples prepared as slurry, is proposed for determination of lead in environmental samples. The samples (20-50 mg, particle size

The development of a method for the determination of trace elements in fuel alcohol by ETV-ICP-MS using isotope dilution calibration.

A method for the determination of Ag, Cd, Cu, Pb and Tl in fuel alcohol by isotope dilution electrothermal vaporization inductively coupled plasma mass spectrometry (ID ETV-ICP-MS) is proposed. The analytes were separated in two groups: Ag and Cu were determined without modifier and Cd, Pb and Tl with the use of Pd as chemical modifier. The employed ETV operational conditions were pyrolysis temperature of 800 degrees C for Cd, Pb and Tl and of 900 degrees C for Ag and Cu and vaporization temperature of 2400 degrees C for both groups. Seven common, one with additive and one anhydrous fuel ethanol samples were analyzed. The spiked and reference isotopes were, respectively, (109)Ag and (107)Ag, (112)Cd and (111)Cd, (63)Cu and (65)Cu, (206)Pb and (208)Pb and (203)Tl and (205)Tl. The added amounts of the enriched isotope material were the same for all samples: 4.6 ng of (109)Ag, 5 ng of (112)Cd, 21.1 ng of (63)Cu, 9 ng of (206)Pb and 0.21 ng of (203)Tl. The blank was bi-distilled ethanol, acidified with 0.3% (v/v) nitric acid, as the samples. The limits of detection (LODs) were calculated as three times the standard deviation of the concentrations in the blank (n=10) and were, in microg L(-1), for Ag: 0.02, for Cd: 0.08, for Cu: 0.1, for Pb: 0.05 and for Tl: 0.001. The obtained concentrations in the samples were in agreement with those obtained by external calibration (EC), according to the paired t-test. The isotope dilution (ID) showed to be a robust, fast and simple calibration technique for the analysis of fuel ethanol.

Direct determination of selenium in urine samples by electrothermal atomic absorption spectrometry using a Zr plus Rh-treated graphite tube and co-injection of Rh as chemical modifier.

Different chemical modifiers for use with electrothermal atomic absorption spectrometry (ET AAS) were investigated in relation to determining the selenium in human urine samples. The samples were diluted in a solution containing 1% v/v HNO3 and 0.02% m/v cetyltrimethylammonium chloride (CTAC). Studying the modifiers showed that the use of either Ru or Ir as the permanent modifier gave low sensitivity to Se and the peak shape was very noisy, while Zr or Rh gave no peak at all. The same occurred when Zr was used in solution. For mixtures of permanent modifiers, Ir plus Rh or Zr plus Rh gave very low sensitivity, Zr plus Rh with co-injection of Ir in solution was also not efficient, Zr plus Rh in solution gave good sensitivity, but the best results were obtained with a mixture of Zr and Rh as the permanent modifier and co-injection of Rh in solution. Using this last modifier, the following dilutions with the HNO3 and CTAC were studied: 1:1, 1:2, 1:3 and 1:4. The best dilution was 1:1, which promoted good sensitivity and a more defined peak shape and made it possible to correct for the background using a deuterium arc lamp. Under these conditions, a characteristic mass of 26+/-0.2 pg was obtained for Se in aqueous solution. Six certified urine samples were analyzed using matrix matching calibration and the measured concentrations were in agreement with the certified values, according to a t-test at the 95% confidence level. Recovery tests were carried out and the recoveries were in the range 100-103%, with relative standard deviation better than 9%. The limit of detection (LOD, 3 sd, n = 10) was 3.0 microg L(-1) in the sample. The treated graphite tube could be used for at least 600 atomization cycles without significant alteration of the analytical signal.

Determination of trace metals in electrolytic copper by ICP OES and ICP-MS

O presente trabalho apresenta um estudo comparativo das técnicas ICP-MS e ICP OES com configuração axial e também de dois métodos diferentes de tratamento das amostras, ou seja, por dissolução total com e sem separação do cobre por eletrodeposição, para as determinações de As, Fe, Mn, Pb, Sb e Sn em amostras de cobre eletrolítico. Amostras comerciais e industriais foram dissolvidas com HNO3 5% v/v e o cobre foi eletrodepositado em meio de HNO3 (1,4% v/v) e H2SO4 (2,0% v/v). Verificou-se que a separação do cobre foi eficiente, contudo se constatou contaminação de Fe e Sn durante o processo de eletrodeposição. As determinações foram realizadas utilizando-se um ICP OES Axial Varian (Vista Pro) e um ICP-MS Perkin Elmer (Elan Sciex 6000). Foi aplicada a calibração externa, com soluções padrão contendo ou não cobre na concentração equivalente à da amostra. Os limites de detecção (3s, n=10) para a técnica de ICP OES foram bastante semelhantes na presença ou não do cobre). Já usando ICP-MS, os limites foram melhores na ausência do cobre. Com o objetivo de estabelecer o nível de significância entre as técnicas de quantificação, ou seja, entre ICP OES e ICP-MS,foi aplicado o teste t emparelhado, que demonstrou, para um nível de confiança de 95%, não haver diferença significativa, tanto para as soluções sem ou com cobre. Os resultados obtidos no presente trabalho demonstraram que as técnicas ICP-MS e ICP OES fornecem resultados similares em determinadas faixas de concentração dos analitos, podendo ambas serem utilizadas, no controle de qualidade do cobre eletrolítico. Contudo, a técnica ICP-MS foi superior em termos de limite de detecção.

Determination of Cd in biological samples by flame AAS following on-line preconcentration by complexation with O,O-diethyldithiophosphate and solid phase extraction with Amberlite XAD-4.

A method for the on-line preconcentration of Cd based on its complex formation with the ammonium salt of O,O-diethylditiophosphate (DDTP) and using the Amberlite XAD-4 resin as a solid support in a column is proposed. Cadmium was detected by flame atomic absorption spectrometry. Different conditions, such as complexing agent concentration, preconcentration time, solutions flow rates and nature and concentration of the eluent were optimized. Different detection limits (LODs) could be established by using different preconcentration times, between 30s and 5min, with corresponding LODs from 5 to 1mugL(-1), respectively. The method was validated by analyzing five biological certified samples. The relative standard deviation was usually around 3%, indicating a very good precision. The found concentrations values are in agreement with the certified ones, according to the t-test, for a confidence level of 95%. Enriched seawaters were also analyzed, and the recoveries were between 93 and 108%. The FI method is very simple and probably can be coupled to other measuring analytical techniques.

Slurry sampling of sediments and coals for the determination of Sn by HG-GF AAS with retention in the graphite tube treated with Th or W as permanent modifiers.

A method for the determination of Sn in slurry samples of sediment and coal by hydride generation graphite furnace electrothermal atomic absorption spectrometry (HG-GF AAS) is proposed. The slurries were prepared by mixing the ground sample (particle size < or =50 microm) with 2.0 mol L(-1) HCl for the sediment samples or with 2.0 mol L(-1) HCl+1.0% v/v HF in a saturated boric acid medium for the coal samples. The slurry was placed in an ultrasonic bath for 30 min, before and after standing for 24 h, with occasional manual stirring. The graphite tube was treated with 0.5 mg of Th or W as a permanent modifier. Sn determination was carried out by electrothermal atomic absorption spectrometry at the optimized retention temperatures of 450 and 300 degrees C for Th and W treatment, respectively. With this coupling, kinetic interference in the formation of the hydrides is avoided, and excellent detection limits can be obtained by using peak height. For the chemical vapor generation device, an optimized volume of 2 mL of sample slurry and an optimized NaBH4 concentration of 5% m/v were employed. The vapor produced was transported and retained on the graphite tube surface, which was further heated for Sn atomization. The accuracy of the method was verified by analyzing five certified sediments and three coals. By using the external calibration against aqueous standard solutions, the results obtained were in agreement with the certified values only for the sediment samples. For the coal samples, an addition calibration curve, obtained for one certified coal, was necessary to achieve accurate results. The obtained limits of detection were 0.03 microg g(-1) for sediment and 0.09 microg g(-1) for coal with Th as permanent modifier. The relative standard deviations were lower than 15%, demonstrating an adequate precision for slurry analysis. Sediment and coal samples from Santa Catarina, Brazil, were also analyzed.

Determination of cadmium in biological samples solubilized with tetramethylammonium hydroxide by electrothermal atomic absorption spectrometry, using ruthenium as permanent modifier.

The feasibility of Ru as a permanent modifier for the determination of Cd in biological samples treated with tetramethylammonium hydroxide (TMAH) by ET AAS was investigated. The tube treatment with Ru was carried out only once and lasted for about 300 atomization cycles. The pyrolysis and atomization temperatures, 750 degrees C and 1300 degrees C, respectively, were chosen from the temperature curves. The sample dissolution procedure was very simple: a sample aliquot was mixed with a small volume of a 25% m/v TMAH solution, the volume was made up to 50 ml and the mixture was kept at 60 degrees C for 1 h. Six certified biological reference materials were analyzed and the obtained Cd concentrations are within the 95% confidence interval of the certified values, proving the accuracy of the proposed procedure for a variety of biological samples. The calibration curve, with correlation coefficient higher than 0.99, was established for a working range up to 10 microg l(-1). The precision was good as demonstrated by relative standard deviations below 3%, except for one sample. The limit of detection (3sigma) was 0.05 microg l(-1) and the characteristic mass was 1.30 pg, obtained in the presence of the Ru modifier.

Efeitos da diclorfenamida sobre a concentraçäo de zinco no humor aquoso e no sangue de cäes / Dicholorphenamide effects on zinc concentration in dog's aqueous humor and blood

Os óligo-elementos, embora presentes em quantidades diminutas no organismo, säo de extrema importância para a vida. O zinco é o segundo óligo-elemento mais abundante do corpo humano, sendo essencial para o desenvolvimento normal dos seres vivos. É componente necessário e integrante da anidrase carbônica, que constitui uma metaloenzima que se encontra em várias formas de isoenzima no corp. Nos processos ciliares de olhos humanos, ela é quase inteiramente pura; mediante a sua inibiçäo, consegue-se, provadamente pela filtraçäo da parede capilar, reduzir a produçäo do humor aquosos e, consequentemente, da pressäo ocular. Entre os inibidores da anidrase carbônica está a diclorfenamida, sendo uma sulfonamida comercializada em nosso meio, somente para uso oral. Este trabalho visou testar o efeito da diclorfenamida sobre o zinco do humor aquoso e do sangue, supondo-se uma interferência do zinco no controle da pressäo ocular; para isto foram estudados, em dezenove cäes, trinta e oito olhos, sendo que para cada cäo, um olho foi controle do outro