A new method based on extraction induced by emulsion breaking for determination of Co and Ni in chocolate bars by graphite furnace atomic absorption spectrometry.

This paper describes a new experimental configuration of extraction induced by emulsion breaking method to extract and determine Ni and Co in chocolate bars by graphite furnace atomic absorption spectrometry. At optimized conditions, the sample (0.08 g) was mixed with 4 mL of extractant solution (4% m/v Triton X-100 and 10% v/v HNO3) in a plastic syringe to form a solid-oil-water emulsion. Then, emulsion breaking was assisted by membrane filtration. The total extraction procedure took approximately 1 min, in opposition to 25 (centrifugation) and 50 min (heating). Extraction yields ranged from 94.8 to 114.3% for Co and from 85.9 to 108.4% for Ni. The limits of detection and quantification were, respectively, 24.73 and 82.45 µg Kg-1 for Co and 49.05 and 163.5 µg Kg-1 for Ni. Recoveries ranged from 92.1 (Ni) to 105.4% (Co).

Multiple anthropogenic influences in the Pará River (Amazonia, Brazil): A spatial-temporal ecotoxicological monitoring in abiotic and biotic compartments.

The mineral wealth of the Amazon region is prone to intense exploration with consequent metals mobilization in ecosystems. Besides that, a number of other anthropogenic activities contribute to the imbalance of this important environment. The Pará River is an important water body in the Amazon basin and is under multiple anthropogenic influences, including disorderly urbanization, port activities and processing of minerals such as bauxite and kaolin. In this study, metals concentrations (Al, Cr, Pb, Ba, Ni, and Mn) in water, sediment and organisms (the fish Cheirocerus goeldii and the shrimp Macrobrachium amazonicum) and biochemical biomarkers (total antioxidant capacity, ACAP and lipid peroxidation, LPO) were analyzed along five points in the Para River with different distances to a center of anthropogenic activity, in three seasonal periods (rainy, transition and dry). Metals concentrations were similar among sites in each seasonal period but Aluminium (Al) presented the highest concentrations among all analyzed metals both in sediment and water considering all sampling points and all seasonal periods. In the dissolved fraction, Al had values above those established by the local environmental agency, especially during the rainy season. In the biotic compartment, both fish and shrimps showed higher concentrations of metals (Al and Ba) in the rainy season compared to the other seasons. Shrimp was more responsive to metal accumulation than fish, showing an adaptive response of biomarkers. Fish showed an increase of LPO in gills for individuals from the point of greater anthropogenic interference during the rainy season, but no differences in metal accumulation. We conclude that there is a seasonal pattern of metals concentration in different environmental compartments. Metal concentration in organisms and biomarkers responses, showed the effect of anthropogenic influences, which was not evident in results from chemical analyses alone, due to the intensive hydrodynamics in the region.

Extraction induced by emulsion breaking to assay Cr, Cu and Mn in asphalt samples by high-resolution continuum source atomic absorption spectrometry and its comparison with other sample preparation methods.

This paper reports the development of a method based on the extraction induced by emulsion breaking (EIEB) for the determination of Cr, Cu and Mn in asphalt by high-resolution continuum source atomic absorption spectrometry. In optimized conditions, the extraction efficiency ranged from 88.6 for Cu to 104.5% for Mn. Measurements were carried out at the primary lines of the three analytes. The limits of detection were 0.02 µg g-1 for Cr, 0.01 µg g-1 for Cu and 7.11 ng g-1 for Mn. The precision, expressed as the relative standard deviation, ranged from 1.0 for Cu to 9.1% for Cr. The performance of the proposed method was compared to previously reported sample preparation procedures, including microwave-assisted acid digestion (MW-AD), ultrasound-assisted acid extraction (USE), emulsification (E), and direct dilution in organic solvent (DD). The parameters evaluated were matrix effects, limits of detection and quantification, characteristic mass, precision, accuracy, sample stability and applicability for routine analysis. The methods most suitable for Cu determination were EIEB, MW-AD, USE and E. For Cr and Mn, the best results were obtained by EIEB, MW-AD and DD procedures.

Collection of polycyclic aromatic sulfur heterocycles from asphalt fumes and quantification by an HPLC-DAD method.

A chromatographic method is described for the separation and quantification of polycyclic aromatic sulfur heterocycles (PASHs) using liquid chromatography coupled with diode array detection (DAD). The PASHs that were investigated in this study were chosen based on their similarity in molecular weight, volatility and polarity of their PAH analogues. The chromatographic separation of the compounds was optimized, and their analytical characteristics were evaluated. The limits of detection and quantification ranged from 0.05 for 2,3,4,7-tetramethylbenzothiophene to 2.16 µg L-1 for thieno[2,3-b]thiophene and from 0.16 for 2,3,4,7-tetramethylbenzothiophene to 6.53 µg L-1 for thieno[2,3-b]thiophene, respectively. Recoveries ranged from 84.9 for benzo[b]benzo[4,5]thieno[2,3-d]thiophene to 110% for dinaphtho[2,1-b:1',2'-d]thiophene. Intermediate precisions and repeatabilities lie between 1.4 and 3.0%, and 0.3 and 1.7%, respectively. The chromatographic method was applied for determination of PASHs directly in asphalt fumes, which were obtained by heating asphalt samples in a homemade closed system. The mutual interference of PAH analogues was also discussed. The method was successfully used for PASH determination in asphalt samples obtained from three different oil refineries in Brazil.

Simultaneous determination of Ba, Co, Fe, and Ni in nuts by high-resolution continuum source atomic absorption spectrometry after extraction induced by solid-oil-water emulsion breaking.

This paper describes the simultaneous determination of Ba, Co, Fe, and Ni in nuts by high-resolution continuum source atomic absorption spectrometry after extraction induced by solid-oil-water emulsion breaking. Extraction yields ranged from 94.9 for Ba to 109.8% for Fe. Simultaneous measurements were carried out at secondary lines of Ba, Co, Fe, and Ni. The limits of detection and quantification were, respectively, 3.819 and 1.146 mg L-1 for Ba, 2.274 and 7.421 µg L-1 for Co, 0.095 and 0.285 mg L-1 for Fe, and 2.138 and 6.614 µg L-1 for Ni. The precision ranged from 3.1 to 4.2%, 1.5 to 8.0%, 1.6 to 6.6%, and 0.4 to 6.1% for Ba, Co, Fe and Ni, respectively. The method accuracy was assessed by recovery tests and comparison of the results obtained by the proposed extraction method with those obtained after acid digestion. Recoveries ranged from 93.5 for Ni to 104.5% for Co.