Distribution of metals in different environmental compartments and oxidative stress biomarkers in Bryconops caudomaculatus (Osteichthyes: Characiformes) from a bauxite mining area in the Eastern Amazon.

The Eastern Amazon is rich in bauxite ore. The extraction and processing of bauxite lead to the mobilization of Aluminum (Al) and other metals in environmental. We evaluated the metals (Al, Mn, Ba, and Cr) concentration in tissue, water, and sediment associated with antioxidant and oxidative damage responses in Bryconops caudomaculatus. The samplings were done in two hydrological periods (post-rain and post-dry periods) and at three points, located at two rivers: one in the surroundings of the mining area (P1) and other inside the mining area, upstream (P2), and downstream (P3). Defense antioxidant system biomarkers analyzed were total antioxidant capacity (ACAP) and glutathione-S-transferase (GST) activity. As an oxidative damage biomarker, the lipoperoxidation (LPO) was evaluated. Metals concentrations in the water and sediment were higher in the post-rain period compared to post-dry period. The water samples were acidic, with dissolved Al concentrations above the values established by local legislation at all points. In the gills, the metals accumulation was higher in fish from in the surrounding and upstream sites, and in the liver, was higher in fish from downstream site. Fish from the surrounding had increased antioxidant defenses, with higher ACAP in all tissues and higher GST in the gills. Consequently, they had lower levels of LPO. Fish from the mining area had decreased antioxidant defenses, with lower ACAP in all tissues and lower GST in the gills. Consequently, they had higher levels of LPO, indicating oxidative stress. The fish muscle was not responsive to GST and LPO at all sites. We conclude that the oxidative stress observed in the gills and liver of B. caudomaculatus from the area modified by the mining activity reflected the local anthropogenic impact status.

Extraction Induced by Emulsion and Microemulsion Breaking for Metal Determination by Spectrometric Methods - A Review.

This review focuses on extraction induced by the destabilization of emulsified systems combined with spectrometric techniques for metal analysis in oily samples. This approach is based on the formation and breaking of an emulsion (extraction induced by emulsion breaking - EIEB) or microemulsion (extraction induced by microemulsion breaking - EIMB) to transfer the analytes from the oil sample to the aqueous phase, which is separated in the process. Its simplicity, speed, and low cost have contributed to its growing popularity among researchers. However, the potential of EIEB and EIMB is far from being fully exploited. Therefore, this paper aims to provide relevant information to expand the applicability of these methods. The principle of the methods is discussed, and a brief description of emulsified systems is presented. The parameters affecting the extraction efficiency and calibration strategy are also critically discussed. Furthermore, the analytical applications of the methods are reviewed. Trends and opportunities in this field are also considered.

Silver nano/microparticle toxicity in the shrimp Litopenaeus vannamei (Boone, 1931).

The effects of silver nano/microparticles (AgP) on juvenile Litopenaeus vannamei shrimp were evaluated through several responses, aiming to use it as a prophylactic and therapeutic method. Shrimps (3.19 ± 0.13 g) were exposed to clear water for 3 h with increasing concentrations of nanosilver (0; 25; 100; and 400 µg/l). After 3 h of exposure, they were transferred to water without nanosilver for 30 days (recovery). The weight gain and weekly growth were not affected by AgNP. Total antioxidant capacity (ACAP) increased in the hepatopancreas (exposure period) and gills (recovery) in shrimp exposed to AgNP. In muscle, ACAP was induced in shrimp exposed to 100 µg/l AgNP (exposure). In the gills, there was an increase in TBARS in shrimp exposed to 100 µg/l AgNP (recovery). In the concentration of protein-associated sulfhydryl groups (P-SH), a decrease was observed in the hepatopancreas (recovery) in the 100 µg/l AgNP treatment. In chromaticity parameters, an increase in reddish tones was observed in shrimp exposed to 100 µg/l AgNP (recovery). An increase in granular hemocytes was verified in shrimp exposed to 25 and 400 µg/l AgNP during exposure. Tissues analyzed histologically showed normal patterns without apoptosis or necrosis processes, and after 30 d of recovery, only in one muscle sample of shrimp exposed to µg/l of AgNP was silver detected. It is concluded that a prophylactic action of short duration (3 h) mostly did not affected the welfare of shrimp L. vannamei and can be considered its use as a therapeutic strategy.

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 iron and nickel as contaminants in multimineral and multivitamin supplements by solid sampling HR-CS GF AAS.

A methodology to assay simultaneously iron and nickel present as contaminants in multimineral and multivitamin supplements was investigated. High-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sample analysis were used. Measurements were done with the secondary lines of Fe (352.604 nm) and Ni (352.454 nm) to avoid spectral interferences. The best temperatures for pyrolysis and atomization for Fe and Ni were 1000 and 2700 °C, respectively. Chemical modifiers were not necessary and no matrix effects were observed. Aqueous standard solutions were used for calibration. The limit of detection was 0.517 µg g-1 for Fe and 0.011 µg g-1 for Ni. The precision ranged from 4.3% to 17% and 4.4-20% for Fe and Ni, respectively. The method accuracy was confirmed by comparing statistically the results obtained by solid sampling with those of sample acid digestion. The proposed methodology was successfully applied to determine both metals in different multimineral and multivitamin supplements.

Simultaneous determination of cobalt and nickel in vitamin B12 samples using high-resolution continuum source atomic absorption spectrometry.

Nickel and cobalt were simultaneously assayed in vitamin B12 formulations by using atomic spectrometry. The proposed method is based on a compromise between the proximity of specific Ni and Co spectral lines and the relative abundances of the analytes in the samples. The analytes were found in concentrations ranging from 9.48 to 26.20µg L(-1) (Ni) and from 156.90 to 279.25mg L(-1) (Co) in the commercial samples of vitamin B12. The limits of detection and quantification were 1.21 and 3.64mg L(-1) for Co and 0.39 and 1.19µg L(-1) for Ni. Sample cleanup was not necessary for the determinations, and the interferences were discussed.