Reinaldo Calixto de Campos

Chemical vapor generation—electrothermal atomic absorption spectrometry: new perspectives☆

Abstract Volatile species of Ag, Cu, Cd, and Zn were generated at room temperature by the addition of sodium tetrahydroborate (III) to an acidified solution of the analytes. The vapor-phase species were rapidly transported to a pre-heated graphite tube, the surface of which was previously treated with Ir as a permanent chemical modifier. The volatile species were trapped at the Ir treated tube surface, and the further heating of the furnace permits their determination by atomic absorption spectrometry. A univariate approach was used to achieve optimized conditions and derive the figures of merit. The limits of detection based on a 3σ b criterion were 10 (1); 0.006 (6×10 −4 ); 28 (2.8) and 1.1 (0.11) ng (μg ml −1 ) for Ag, Cd, Cu and Zn, respectively. Precision of replicate measurements was typically approximately 10% R.S.D. Using a transfer line as short as possible should minimize losses of analyte during the transport to the graphite furnace. The overall efficiency of the volatile species generation and trapping process estimated for silver was 13%.

A novel report of metallothioneins in fish bile: SDS-PAGE analysis, spectrophotometry quantification and metal speciation characterization by liquid chromatography coupled to ICP-MS.

Metallothioneins (MT) are a validated biomarker for metal exposure. In fish they are usually determined in the liver, while some studies have observed MT in kidney, muscle and gills. There are, however, no reports on MT in fish bile. This study aimed to verify if these proteins are present in fish bile, if they can be used as biomarkers for metal exposure and to characterize the metal speciation present in the different species. Three independent methods to verify MT presence in fish bile were conducted: 1D/2D gel electrophoresis, spectrophotometric analyses and SEC-HPLC-ICP-MS. Results show that all methods verified the presence of these proteins in fish bile, while SEC-HPLC-ICP-MS also characterized also characterized metals responsible for the contamination of the studied sites. Quantification was successfully conducted by two methods, densitometry (1D electrophoresis) and spectrophotometry, and the data indicates that bile MTs follow the same trend as in liver. Therefore, Biliary MT show the potential to be used the same way as MT from other matrices in metal exposure studies, with the advantage of being a simpler matrix and showing the possibility of not sacrificing the animals, as chronic duct cannulation is available.

Scanner image analysis in the quantification of mercury using spot-tests

A digital image analysis procedure for mercury quantification based on the analysis of the color developed in a spot-test derived reaction using a commercial scanner is described. The color intensity is related to the concentration in the original sample. Digital image analysis of the developed color was used to establish a quantitative relationship between the color components and the mercury concentration. Different color separation models were compared and their sensitivity to the variation of the mercury concentration was evaluated. The Hue-Lightness-Saturation (HLS) model provided the best results, showing a linear relationship between the Hue value and the mercury concentration. The procedure was used for the analysis of interlaboratorial fish samples and good concordance between found and reported values was found. The detection limits were estimated from the confidence bands of the analytical curves. For a calibration interval of 100 to 600 ng, a detection limit of 0.007 µg g-1 (wet weight) was found.

Fish Metalloproteins as Biomarkers of Environmental Contamination

Fish are well-recognized bioindicators of environmental contamination. Several recent proteomic studies have demonstrated the validity and value of using fish in the search and discovery of new biomarkers. Certain analytical tools, such as comparative protein expression analyses, both in field and lab exposure studies, have been used to improve the understanding of the potential for chemical pollutants to cause harmful effects. The metallomic approach is in its early stages of development, but has already shown great potential for use in ecological and environmental monitoring contexts. Besides discovering new metalloproteins that may be used as biomarkers for environmental contamination, metallomics can be used to more comprehensively elucidate existing biomarkers, which may enhance their effectiveness. Unfortunately, metallomic profiling for fish has not been explored, because only a few fish metalloproteins have thus far been discovered and studied. Of those that have, some have shown ecological importance, and are now successfully used as biomarkers of environmental contamination. These biomarkers have been shown to respond to several types of environmental contamination, such as cyanotoxins, metals, and sewage effluents, although many do not yet possess any known function. Examples of successes include MMPs, superoxide dismutases, selenoproteins, and iron-bound proteins. Unfortunately, none of these have, as yet, been extensively studied. As data are developed for them, valuable new information on their roles in fish physiology and in inducing environmental effects should become available.

Guiana Dolphins (Sotalia guianensis, Van Benédén 1864) as Indicators of the Bioaccumulation of Total Mercury along the Coast of Rio de Janeiro State, Southeastern Brazil

Total mercury (Hg) was determined in muscle tissue of 20 Guiana dolphins stranded along the coast of Rio de Janeiro state, Brazil, with a mean of 1.07xa0μg/g wet weight. Mercury concentrations were positively related to body length, possibly related to the capacity of the dolphins to bioaccumulate this element throughout life. The Hg concentrations were not significantly different between males and females, although females (1.08xa0μg/g) showed slightly higher levels than males (1.04xa0μg/g). Concentrations were low when compared to results of studies carried out with small cetaceans in the Northern Hemisphere, and with previous studies in the Southeastern Brazil.

On-line mercury and methylmercury pre-concentration by adsorption of their dithiophosphoric acid diacyl ester chelates on a C18 column and cold-vapor atomic-absorption detection

Abstract. The pre-concentration of mercury(II) and methylmercury by adsorption of their dithiophosphoric acid diacyl ester (DDTP) chelates on a C18 column, then detection with cold-vapor atomic-absorption spectrometry was investigated. Conditions such as sample pH, reductant and chelating agent flow and concentration, and eluent and carrier gas flow were optimized. Optimization was performed by use of evolutionary operation with a proper factorial design. At a sample flow of 5.3xa0mLxa0min–1 and a loading time of 4.5xa0min, column adsorption efficiency ranged from 88 to 93% for both species. Detection limits down to 10xa0ngxa0L–1 were obtained at a sample throughput of 12xa0h–1. There was good agreement between found and certified values in the analysis of certified reference materials after their microwave-assisted mineralization with HNO3 and H2O2.

Fish bile as a biomarker for metal exposure.

Fish accumulate several trace elements in muscle, gills and liver, however studies also indicate that metals can be excreted through bile. Since metal contamination leads to modifications in bile composition, biliary excretion offers an alternative way to evaluate the presence of trace-elements. Bile is easier to obtain than other organs and presents a simpler matrix, making it easier for chemical pre-treatment. To verify if bile can be useful as a biomonitoring tool for metal contamination, liver and bile trace element concentrations were determined and correlated. The Artificial Neural Networks statistical technique was used to verify if liver trace-element quantification could be substituted by bile analysis. Results show that significant correlations were obtained between trace elements in bile and liver and the ANN validated the hypothesis that certain trace-elements in bile could be utilized instead of liver trace-elements. Further studies in this field are of interest to further validate this biomarker.

Determination of platinum originated from antitumoral drugs in human urine by atomic absorption spectrometric methods

Cisplatin and carboplatin are the most common platinum-based drugs used in cancer treatment. Pharmacokinetic investigations, the evaluation of the body burden during the treatment, as well as baseline levels of platinum in humans have attracted great interest. Thus, accurate analytical methods for fast and easy Pt monitoring in clinical samples become necessary. In the present study atomic absorption spectrometric methods for the determination of platinum in the forms of cisplatin and carboplatin in human urine were investigated. Platinum, in these different forms, could be determined in urine, after simple sample dilution. Regarding electrothermal atomic absorption spectrometry, the optimum parameters were defined by a central composite design optimization. Multiplicative matrix effects were overcome by using a mixture of HCl and NaCl as modifier. The limit of detection (LOD) was 0.004 mgL(-1) of platinum in the original sample. For the analysis of more concentrated samples, high resolution continuous source flame atomic absorption spectrometry was also investigated. Flame conditions were optimized by a multivariate D-optimal design, using as response the sum of the analyte addition calibration slopes and their standard deviations. Matrix matched external calibration with PtCl(2) calibration solutions, was possible, and the LOD was 0.06 mgL(-1) in the original sample. The results obtained by the proposed procedures were also in good agreement with those obtained by an independent comparative procedure.

Determinação da composição mineral de diferentes formulações de multimistura

The multimistura is a broad distributed product in Brazil, first formulated by Dr. Clara Brandao and introduced by the CNBB (National Conference of Brazil Bishops), Children Pastoral as part of its activities in the health basic attention area. Its formula varies according to local ingredient availability but basically is compounded by non-conventional habitual diet kinds of food, among them are bran, egg shelf powder, dark green leaves and nuts and seeds. It is considered as a nutritional complement used to supply nutritional deficiencies mostly in underweight children. However, a controversy was created due to the real bioavailability of its nutrients and the presence in it of non-nutritional factors. These factors have restricted its use in this way. This research had as an objective measure the mineral composition (Ca, Cu, Fe, K, Mg, Mn, P, Zn) of various multimistura formulations, by the espectrophotometry of atomic absorption, in a way to know its profile as a mineral nutritional complement for children up to five years old. By the results obtained it was seen that, in 80% of the samples, the ash content (fixed mineral rest) was below the minimum value expected in its Technical Rules for Identity Fixation and Quality of Mixtures Based in Cereal Bran. (RDC n. 53, 2000) where, the recommend dose for the multimistura in this age range does not signoficantly reache the DRI (Daily Recommended Ingestion). By this way, the formulations studied cannot be used as a nutritional complement for these minerals.

First-time report of metalloproteinases in fish bile and their potential as bioindicators regarding environmental contamination.

Gallbladder bile from 2 fish species, mullet (Mugil liza) and tilapias (Tilapia rendalli), contain substantial matrix metalloproteinases (MMPs). Extensive purification studies were conducted in order to obtain workable samples for SDS-PAGE and zymography analysis. Proteinase activities were assayed by gelatin substrate zymography. Several protein bands were observed, corresponding to molecular weights of 200, 136, 43, 36, 34, 29, 23 and 14 kDa in mullet bile and 179, 97, 79, 61, 54, 45, 36, 33 and 21 kDa in tilapia bile. Specific inhibitor studies were conducted, in which MMPS were inhibited by EDTA and 1,10 phenanthroline, but not by serine and cysteine protease inhibitors, such as phenylmethylsulfonyl fluoride (PMSF) and transepoxysuccinyl-l-leucylamido-l-guanidino butane (E-64), confirming the proteinase identities as MMPs. Differences in proteinase expression were observed in fish from a contaminated and reference site. Some studies regarding MMPs in different fish tissues exist, however this is the first study conducted in fish bile, and their involvement in detoxification processes and organism protection against the effects of aquatic contaminants may be a possibility.