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In order to better understand the role of the Hg atmospheric samples, in this work we investigated how much Hg there is in a commercially available biodiesel/diesel mix (B7, 7 % v v-¹ biodiesel to ...

In the present study, the Hg levels in freshly collected polychaete species and their associated sediments were evaluated from Todos os Santos Bay, Northeastern Brazil. Additionally, it was also measured the Hg distribution along the annelids' body parts (anterior region, abdomen, and posterior region). Total Hg concentration was as follows: 13.6-144 μg kg

A new analytical protocol has been developed for the determination of mercury in surface sediments using dithiothreitol (DTT) as a new chelating reagent for the extraction. This protocol requires a small sample mass (250 mg), 4.0 mL of a 0.1 M (pH = 9.0) aqueous DTT solution, and sonication for 30 min, followed by cold vapor atomic fluorescence spectrometry (CV-AFS). The limits of detection and quantification determined were 6 and 18 ng g−1, respectively. The method was validated using three standard reference materials, SRM NIST 1646a, PACS-2, and MESS-3, with recoveries in the range of 102-124%. The new analytical protocol was successfully applied in riverine surface sediments, revealing concentrations in the range of 220-340 ng g−1. The results obtained by CV-AFS were compared to those obtained by DMA-80 (direct mercury analyzer). The linear regression equation obtained was [CV-AFS] = (0.91 ± 0.07)[DMA-80] + (0.04 ± 0.02), revealing no systematic difference between the analytical methods. Hence, the proposed method does not require the complete digestion of the sediment, and was found to be comprehensive, simple, accurate and suitable to be employed for determination of mercury in sediment samples.

We determined depth profiles of total mercury (T-Hg) in six 210Pb-dated sediment cores from Todos os Santos Bay to reconstruct the history of anthropogenic Hg accumulation. We also assessed superficial sediments samples from five estuaries. T-Hg concentrations (5–3500 μg kg−1) presented a large spatial and temporal variability. T-Hg concentrations in Ribeira Bay increased up to 200-fold along time, whereas the fluxes of T-Hg are substantially higher (up to 10,000 fold) than present-day wet deposition for industrialized areas. Sedimentary records indicate that a chlor-alkali plant has been the main source of Hg pollution until the present, although the T-Hg records suggest that harbor, shrimp farming, and oil refinery activities, besides Hg atmospheric depositions, are important across the bay. Sediments in the Ribeira Bay act as an important Hg sink. If sediments are eroded or disturbed, they may release Hg, thus posing a serious risk to wildlife and ecosystem health. Capsule Sedimentary cores provide data on preindustrial levels and also anthropogenic fluxes of Hg for the appraisal of the magnitude, processes and potential risks of the contamination.

In this work, the redox activity of fine diesel/biodiesel particulate matter (PM2.5) was studied in order to approach its toxicity from reactive oxygen species, due to adverse effects it may cause to human health. The oxidative potential was measured by the dithiothreitol (DTT) assay in order to study the relative contribution of water-soluble transition metals, polycyclic aromatic compounds (PAH), nitro-PAH, and quinones. It was analyzed a total of 24 samples collected from primarily diesel/biodiesel-exhausted particles from buses. The rate concentrations of PM2.5 redox activity ranged 0.020-0.069 nmol min-1 μg-1, with median at 0.040 nmol min-1 μg-1 (on average, 0.042 ± 0.005 nmol min-1 μg-1 for morning, 0.033 ± 0.007 nmol min-1 μg-1 for afternoon and 0.045 ± 0.009 nmol min-1 μg-1 for night). The transition metals appear to dominate the DTT response, since they were responsible up to 89% of redox activity measured in the samples. Apparently, the metal fraction contained in PM2.5 demonstrated a greater ability to catalyze reactions that promote the formation of reactive oxygen species when compared to organic compounds. It was observed that the oxidative potential of PM2.5 particles emitted from diesel/biodiesel (B7) is similar to diesel-emitted particles.

A simple method has been developed to determine antimony and lead in pewter alloy cups produced in Brazil, using fast sequential determination by high-resolution continuum source flame atomic absorption spectrometry. The samples were dissolved in HCl and H(2)O(2), employing a cold finger system in order to avoid analyte losses. The main resonance line of lead at 217.001 nm and a secondary line of antimony at 212.739 nm were used. The limits of detection for lead and antimony were 0.02 and 5.7 mg L(-1), respectively. The trueness of the method was established by recovery tests and comparing the results obtained by the proposed method with those obtained by inductively coupled plasma optical emission spectrometry. The results were compared using a student's t-test and there was no significant difference at a 95% confidence interval. With the developed methods, it was possible to determine accurately antimony and lead in pewter samples. The lead concentration found in the analysed samples was around 1 mg g(-1), which means that they are not lead free; however, the content was below the maximum allowed level of 5 mg g(-1). The antimony content, which was found to be between 40 and 46 mg g(-1), is actually of greater concern, as antimony is known to be potentially toxic already at very low concentrations, although there is no legislation yet for this element.

This paper presents the validation of a system for sample digestion using a digester block/ cold finger to determine the lead content in vegetables by electrothermal atomic absorption spectrometry (ETAAS). After mineralization, lead contents were determined by ETAAS using a calibration curve based on aqueous standards prepared in 2.60 M nitric acid solutions containing 5 μg ammonium phosphate as chemical modifier. A pyrolysis temperature of 900°C and atomization temperature of 2000°C were used. This method allowed the determination of lead with a characteristic mass of 35 pg; LOD and LOQ of 0.6 and 2 ng/g, respectively, were found. The precision was investigated in terms of reproducibility and repeatability. Reproducibility was estimated by analysis of nine different portions of a certified reference material (CRM) of spinach leaves, and the repeatability was determined through the analysis of nine aliquots of the same solution. The reproducibility and repeatability were found to be 4.27 and 2.94% RSD, respectively. The accuracy was confirmed by analysis of whole meal flour, spinach leaves, and orchard leaves CRMs, all furnished by the National Institute of Standards and Technology. Lead contents were measured using the newly developed technique in 11 different potato samples. The lead contents ranged from 12.80 to 69.27 ng/g, with an average value of 28.59 ng/g. These values were in agreement with data reported in the literature.

Inductively coupled plasma optical emission spectrometry was used to determine the elements present in Chinese cabbage (Beta vulgaris). The accuracy of the method was confirmed by analysis of a certified reference material of spinach leaves. The study involved 57 samples that were collected in 13 Brazilian cities. Average concentrations of elements found per gram of Chinese cabbage were as follows: 3.44 mg g−1 sodium, 5.09 mg g−1 potassium, 1.25 mg g−1 phosphorous, 0.85 mg g−1 calcium, 0.49 mg g−1 magnesium, 2.79 μg g−1 manganese, 9.50 μg g−1 iron, 0.74 μg g−1 copper, 14.28 μg g−1 zinc, and 6.44 μg g−1 strontium. Principal component analysis and hierarchical cluster analysis demonstrated that there is no systematic difference in the mineral composition between the cabbage samples that were analyzed.

The method allowed simultaneous characterization of PAHs, nitro-PAHs and quinones in atmospheric particulate matter. This method employs a miniaturized micro-extraction step that uses 500 μL of an acetonitrile-dichloromethane mix and instrumental analysis by means of a high-resolution GC-MS. The method was validated using the SRM1649b NIST standard reference material as well as deuterated internal standards. The results are in good agreement with the certified values and show recoveries between 75% and 145%. Limit of detection (LOD) values for PAHs were found to be between 0.5 pg (benzo[a]pyrene) to 2.1 pg (dibenzo[a,h]anthracene), for nitro-PAHs ranged between 3.2 pg (1-nitrobenzo[e]pyrene) and 22.2 pg (3-nitrophenanthrene), and for quinones ranged between 11.5 pg (1,4-naphthoquinone) and 458 pg (9,10-phenanthraquinone). The validated method was applied to real PM10 samples collected on quartz fiber filters. Concentrations in the PM10 samples ranged from 0.06 to 15 ng m(-3) for PAHs, from

In this paper, a method for the determination of mercury in phosphate fertilizers using slurry sampling and cold vapor atomic absorption spectrometry (CV QT AAS) is proposed. Because mercury (II) ions form strong complexes with phosphor compounds, the formation of metallic mercury vapor requires the presence of lanthanum chloride as a release agent. Thiourea increases the amount of mercury that is extracted from the solid sample to the liquid phase of the slurry. The method is established using two steps. First, the slurry is prepared using the sample, lanthanum chloride, hydrochloric acid solution and thiourea solution and is sonicated for 20 min. Afterward, mercury vapor is generated using an aliquot of the slurry in the presence of the hydrochloric acid solution and isoamylic alcohol with sodium tetrahydroborate solution as the reducing agent. The experimental conditions for slurry preparation were optimized using two-level full factorial design involving the factors: thiourea and lanthanum chloride concentrations and the duration of sonication. The method allows the determination of mercury by external calibration using aqueous standards with limits of detection and quantification of 2.4 and 8.2 μg kg−1, respectively, and precision, expressed as relative standard deviation, of 6.36 and 5.81% for two phosphate fertilizer samples with mercury concentrations of 0.24 and 0.57 mg kg−1, respectively. The accuracy was confirmed by the analysis of a certified reference material of phosphate fertilizer that was provided by the National Institute of Standards & Technology (NIST). The method was applied to determine mercury in six commercial samples of phosphate fertilizers. The mercury content varied from 33.97 to 209.28 μg kg−1. These samples were also analyzed employing inductively coupled plasma mass spectrometry (ICP-MS). The ICP-MS results were consistent with the results from our proposed method.

The homogeneity and stability of metals were tested in a candidate laboratory reference material of soy leaves. Inductively coupled plasma-optical emission spectrometry was used to quantify calcium, magnesium, manganese, iron, zinc, copper, and vanadium. A 6 kg amount of the material, which was dried, ground, and classified as mesh 60, was distributed among 100 bottles. The between-bottle homogeneity test was established by analyzing two subsamples from nine bottles. For the within-bottle test, five determinations of each element of a single bottle were performed. The stability test was performed at temperatures of –10, +27, and +40°C, and after storage times of 4, 12, 24, and 52 weeks. The obtained results indicated that the material was homogeneous and stable under the conditions studied.

This work describes the optimization and validation of a direct method employing electrothermal atomic absorption spectrometry (ET AAS) for the determination of cadmium in wine. The optimization step was carried out using a two-level full factorial design, involving the followings factors: pyrolysis time (10 s) and temperature (600 ºC), atomization temperature (1300 ºC) and modifier mass (15 µg). Under the optimized conditions, a characteristic mass of 0.7 pg and limits of detection and quantification of 0.030 and 0.100 µg L-1, respectively, were obtained using a sample volume of 20 µL. The precision expressed as relative standard deviation (RSD %) was 0.30, 0.37 and 0.49% for wines with cadmium concentrations of 1.286, 0.266 and 0.356 µg L-1, respectively. The accuracy of the new direct determination methodology applying ET AAS was assessed by comparison with an acid digestion methodology, also with determination by ET AAS, using five wine samples. The proposed method was applied for the determination of cadmium in 30 Brazilian wine samples. The cadmium content varied from 0.146 to 1.563 µg L-1; all these values are lower than the permissible maximum level stipulated by the International Organization of Vine and Wine (OIV) and also by Brazilian legislation, which is 10 µg L-1. O presente trabalho descreve a otimização e validação de um método para determinação direta de cádmio em amostras de vinho por espectrometria de absorção atômica com atomização eletrotérmica (ET AAS). A otimização foi realizada empregando um planejamento fatorial completo de 2 níveis, incluindo os fatores: tempo (10 s) e temperatura de pirólise (600 ºC), temperatura de atomização (1300 ºC) e massa de modificador (15 µg). Sob as condições otimizadas, foi encontrada uma massa característica de 0,7 pg, limite de detecção e quantificação de 0,030 e 0,100 µg L-1, respectivamente, para um volume de amostra de 20 µL. A precisão foi de 0,30, 0,37 e 0,49% (RSD) para amostras de vinho com concentrações de 1,286, 0,266 e 0.356 µg L-1, respectivamente. A exatidão da metodologia de determinação direta empregando ET AAS foi avaliada por comparação usando um método de digestão ácida e determinação também por ET AAS para cinco amostras de vinho. O método foi aplicado para determinação de cádmio em 30 amostras de vinhos brasileiros. A concentração de cádmio variou de 0,146 a 1,563 µg L-1, cujos valores estão abaixo do nível máximo permitido pela Organização Internacional de Vinha e Vinho (OIV) e pela legislação brasileira, 10 µg L-1.

In this paper, we proposed a procedure for the determination of iron(II) and total iron in wine samples employing molecular absorption spectrophotometry. The ligand used is 2-(5-bromo-2-pyridylazo)-5-(diethylamino)-phenol (Br-PADAP) and the chromogenic reaction in absence or presence of ascorbic acid (reducing agent) allows the determination of iron(II) or total iron, respectively. The optimization step was performed using a multivariate technique (Box Behnken design) involving the factors pH, acid ascorbic concentration and reaction time. The method allows the determination of iron(II) and iron(III) in wine samples, with limits of detection and quantification 0.22 and 0.72 microg L(-1), respectively. The precision expressed as relative standard deviation (R.S.D.) was 1.43 and 0.56% (both, n=11) for content of iron(II) in wine samples of 1.68 and 4.65 mg L(-1), and 1.66 and 0.87% (both, n=11) for content of total iron in wine samples of 1.72 and 5.48 mg L(-1). This method was applied for determination of iron(II) and total iron in six different wine samples. In these, the iron(II) content varied from 0.76 to 4.65 mg L(-1) and from 1.01 to 5.48 mg L(-1) for total iron. The results obtained in the determination of total iron by Br-PADAP method were compared with those that were performed after complete acid digestion in open system and determination of total iron employing FAAS. The method of regression linear was used for comparison of these results and demonstrated that there is no significant difference between the results obtained with these two procedures.

A fast and simple procedure is proposed for determination of manganese in corn flour samples employing slurry sampling and electrothermal atomic absorption spectrometry. To evaluate the particle size scanning electron microscopy was used. Slurries were prepared by weighing approximately 100 mg of sample, adding 0.014 mol L−1nitric acid, and a solution containing 1% Triton X-100. An ultrasonic bath was employed for slurry homogenization. Analytical variables including temperature program of the graphite furnace, nitric acid concentration, amount of sample and sonication times were studied. The pyrolysis and atomization temperatures established during the optimization step were 1200 and 2100 °C, respectively, using 10 μg Pd + 3 μg Mg as the chemical modifier. The limits of detection and quantification obtained were 0.006 and 0.020 μg g−1, respectively. A characteristic mass of 0.97 pg was obtained. The precision was evaluated for a sample containing 2.17 μg g−1 of manganese and 2.6% relative standard deviation was found (n = 10). The accuracy was assessed by the analysis of two certified reference materials: NIST SRM 1568a—Rice Flour and CRM 189—Wholemeal Flour. Some experiments demonstrated that the calibration can be performed employing the external calibration technique using aqueous standards. For comparison and validation of the procedure proposed, the samples were also analyzed after complete decomposition and determined by ETAAS and good precision was obtained (at 95% confidence level). In this way, no statistical difference was observed between the results obtained by both the procedures performed. The proposed procedure has been applied for manganese determination in six samples acquired in supermarkets of Salvador (Brazil) and values varied from 0.623 to 2.17 μg g−1.

Aluminium was used as a chemical modifier for the determination of lead in sugar cane spirit samples by electrothermal atomic absorption spectrometry (ET-AAS). Pyrolysis temperature, pyrolysis time and atomisation temperature were 800 °C, 20 s and 1800 °C, respectively. The aluminium mass was 3 µg. Lead was quantified with limits of detection and quantification of 0.14 and 0.47 µg L−1, respectively, and a characteristic mass of 24 pg. Analyte addition experiments demonstrated that external calibration can be performed with aqueous standards. The precision, expressed as relative standard deviation (RSD%), was 3.11% for a sample with a lead concentration of 3.00 µg L−1. There is currently no certified reference material for sugar cane spirits, so a standard reference material of orchard leaves was used to confirm accuracy. The proposed method was used to determine the lead content of five sugar cane spirit samples from Salvador City, Brazil. Their lead contents varied from 3.00 to 19.61 µg L−1. The samples were also analysed by inductively coupled plasma mass spectrometry (ICP-MS) after acid digestion in a closed system. No statistical difference was observed between the results obtained by both methods.