An approach of cobalt recovery from waste copper converter slags using pig iron as capturing agent and simultaneous recovery of copper and tin.

Massive amounts of waste copper converter slags have been produced from pyrometallurgical extraction of copper from copper concentrates, and the disposal of them in landfills creates serious environmental problems. However, this converter slag contains numerous valuable heavy metals, including copper, cobalt and tin etc. In this research, due to similar properties of iron and cobalt, pig iron with a low melting point was creatively used as capturing agent for cobalt recycling in a smelting reduction. The recovery of copper and tin was also studied. The phase transformation during reduction process was clarified by X-ray diffraction and Scanning electron microscope-energy dispersive spectrometer analyses. After the reduction performed at 1250 °C, the copper, cobalt and tin were recovered in a copper-cobalt-tin-iron alloy. The addition of pig iron improved cobalt yield, which was ascribed to the enrichment of cobalt in an iron-cobalt alloy phase. This decreased activity of the reduced cobalt and promoted reduction of cobalt oxide. As a result, the cobalt yield had a significant increase from 66.2% to 90.1% by adding 2% pig iron. Similarly, the copper also accelerated tin recovery through the formation of a copper-tin alloy. The copper and tin yields reached 94.4% and 95.0%, respectively. This work provided a high efficiency method to recover copper, cobalt and tin from waste copper converter slags.

Toxic Metals and Metalloids in Infant Formulas Marketed in Brazil, and Child Health Risks According to the Target Hazard Quotients and Target Cancer Risk.

Children are highly vulnerable to chemical exposure. Thus, metal and metalloid in infant formulas are a concern, although studies in this regard are still relatively scarce. Thus, the presence of aluminum, arsenic, cadmium, tin, mercury, lead, and uranium was investigated in infant formulas marketed in Brazil by inductively coupled plasma mass spectrometry, and the Target Hazard Quotients (THQ) and Target Cancer Risk (TCR) were calculated in to assess the potential risk of toxicity for children who consume these products continuously. Aluminum ranging from 0.432 ± 0.049 to 1.241 ± 0.113 mg·kg-1, arsenic from 0.012 ± 0.009 to 0.034 ± 0.006 mg·kg-1, and tin from 0.007 ± 0.003 to 0.095 ± 0.024 mg·kg-1 were the major elements, while cadmium and uranium were present at the lowest concentrations. According to the THQ, arsenic contents in infant formulas showed a THQ > 1, indicating potential health risk concerns for newborns or children. Minimal carcinogenic risks were observed for the elements considered carcinogenic. Metabolic and nutritional interactions are also discussed. This study indicates the need to improve infant formula surveillance concerning contamination by potentially toxic and carcinogenic elements.

Health Risks for a Rural Community in Bokkos, Plateau State, Nigeria, Exposed to Potentially Toxic Elements from an Abandoned Tin Mine.

The past mining activities in Bokkos Local Government Area (LGA) were performed in an uncontrolled way and gave rise to many abandoned ponds now serving as domestic and irrigation water sources. Past research focused mainly on the environmental impact, and we show for the first time what the human health risk through consumption of contaminated food crops is in these communities. This study was designed to determine the level of Potentially Toxic Elements (PTEs) contamination in pond water, soil, and food crops and assess the health risk of inhabitants in the abandoned tin mining community in Bokkos LGA. Samples of the mining pond water, soil, and selected food crops from farms irrigated with the pond water: bitter leaf (Vernonia amygdalina), pepper (Piper nigrum), okra (Albelmoschus esculentus), maize (Zea mays), sweet potato (Ipomoea batatas), and Irish potato (Solanum tuberosum) were analyzed for each of the eight PTEs (viz. Cu, Cr, Fe, Mn, Ni, Zn, Cd, and Pb) using inductively coupled plasma optical emission spectrometry (ICP-OES). The results obtained showed that the levels of all the PTEs analyzed in the soil, pond water, and selected food crops except for Fe and Mn in soil and Cd in sweet potato were greater than their corresponding background area values (p < 0.05). Also, the mean concentrations of all the PTEs except for Cu in pond water were significantly (p < 0.05) higher than the WHO maximum permissible limit. With the exception of Fe, Ni, and Zn for pepper and okra, Cu and Fe for maize grains as well as Cu, Ni, and Zn for sweet and Irish potatoes and Fe and Cd for sweet potato, the mean concentrations of PTEs in the food crops were significantly higher than WHO maximum permissible limit. The EF values of Cd (0.39); Cu (3.59) and Ni (2.81); Cr (9.38) and Pb (17.84); and Mn (178.13) and Zn (83.22) classified the soil as minimally, moderately, significantly, and extremely highly enriched, respectively. The PI values of all the PTEs in the soil studied were all greater than 5, indicating that the soils were severely contaminated. There was evidence that food crops significantly bioaccumulated PTEs either as a result of contaminated soil and/or irrigation water. The bioaccumulation was not uniform and was dominated by transfer from the polluted irrigation water. The bitter leaf, okra, and to some extent maize had the highest transfer of PTEs, and Mn, Cu, and Zn had the highest bioaccumulation in the food crops investigated. The hazardous index (HI) for the eight PTEs through the consumption of food crops was 107 for children and 33 for adults which greatly exceeded the recommended limit of 1, thus indicating that possible health risks exist for both local children and adults. For every PTE, the values of HI for children are many-fold higher than those for adults, which is of particular concern due to the high HI values for Pb found for maize consumption, a typical staple food. The cancer risk values for Cr and Ni for all the food crops were within 10-3-10-1 which is several fold higher than the permissible limits (10-6 and < 10-4) indicating the high carcinogenic risk. It can be concluded based on the results and risk assessment provided by this study that human exposure to mining pond water and soil in farms around the mining pond through the food chain suggests the high vulnerability of the local community to PTE toxicity. Long-term preventive measures to safeguard the health of the residents need to be put in place.

Hydrochemical evaluation of groundwater quality and human health risk assessment of trace elements in the largest mining district of South Khorasan, Eastern Iran.

The groundwater resources of mining areas have been in a challenging condition in terms of metal pollution and human health. Therefore, this study investigated the concentration of cobalt (Co), molybdenum (Mo), selenium (Se), tin (Sn), and antimony (Sb) in groundwater samples (wells, qanats, and springs) in a heavily contaminated mining district, South Khorasan, Eastern Iran. Human health risk of the studied metals to target groups was assessed, and water quality of the studied groundwater was investigated in the study area. A total of 367 sampling sites (279 wells, 74 qanats, and 14 springs) in South Khorasan Province were selected to collect the groundwater samples from June to July 2020. Sampling was performed thrice for each sampling point, and hydrochemical parameters were evaluated using a portable multiparameter. Inductively coupled plasma mass spectrometry (ICP-MS) was used to detect the metal concentrations. Results showed an order of Se > Mo > Sn > Co > Sb, and hazard index (HI) demonstrated a warning condition for south of South Khorasan (drinking application), southwest of South Khorasan (Irrigation application), and east and center of South Khorasan (drinking-irrigation application). Hydrochemical parameters showed a classification of "Na + K type" and "Mixed Ca-Mg-Cl type" with an overall group of "Na-Cl-HCO3" for sampled waters. Ficklin-Caboi diagram depicted a classification of "near-neutral low metal," and Schoeller diagram classified studied groundwater as "good" for drinking and irrigation consumptions and "Na-Cl" type based on ion balance diagram. Based on the correlation analysis, positive relationships were recorded among EC, TDS, Cl-, Na+, sulfate, Ca2+, salt, total hardness, Mg2+, ammonia, and K+ measured in the water samples. In essence, arid regions of the world greatly rely upon groundwater resources for drinking and irrigation consumptions, and mining districts with a heavy load of active mines can be a serious threat to the groundwater quality and human health.

Speciation of tin ions in oxide glass containing iron oxide through solvent extraction and inductively coupled plasma atomic emission spectrometry after the decomposition utilizing ascorbic acid.

Determining the concentrations of different Sn ions in glass containing iron oxide by wet chemical analysis is a challenge because a redox reaction occurs between Sn2+ and Fe3+. A chemical analysis method for determining the concentrations of Sn2+ and Sn4+ in soda lime glass containing iron oxide was proposed. A mixture of ascorbic acid, hydrochloric acid, and hydrofluoric acid was used to decompose the sample in a vessel with nitrogen flow. Ascorbic acid functioned as a reductant for Fe3+. Subsequently, the Sn2+ were separated as a diethyldithiocarbamate complex. Furthermore, inductively coupled plasma atomic emission spectroscopy was used to determine the concentrations of Sn4+ and total Sn, from which the concentration of Sn2+ can be calculated. The results were validated by comparing ratios of Sn2+ to total Sn to results obtained using Mössbauer spectroscopy. The results were in agreement, thereby validating the use of the proposed approach.

Breast cancer and urinary metal mixtures in Mexican women.

Humans are environmentally exposed to many metals throughout their lives. Simultaneous exposure to several metals could result in synergistic or antagonistic toxicological effects among them; however, the information on exposure to mixtures of metals and breast cancer (BC) is scarce. The objective of this report was to compare metals considered human carcinogens, individually and as mixtures, in women with and without BC. This is a secondary analysis of a population-based case-control study that was carried out from 2007 to 2011 in Northern Mexico. A total of 499 histologically confirmed BC cases and 499 controls were included. Information about sociodemographic, lifestyle and reproductive characteristics was obtained by in-person interviews. Urinary concentrations of aluminum (Al), cadmium (Cd), chromium (Cr), nickel (Ni), lead (Pb), antimony (Sb), cobalt (Co), molybdenum (Mo), tin (Sn), and vanadium (V) were determined by inductively coupled plasma triple quadrupole. Metal mixtures were identified by principal component analysis with creatinine-corrected metals. Over 90% of subjects had metal measurements above the detection limit except tin (86%) and antimony (78.4%). After adjusting by selected covariables, we observed that the individual urinary concentrations of V, Co, and Mo were lower among cases compared to controls; in contrast to Sn that had higher concentrations. We identified two principal component mixtures with opposite relationships with BC: Cr, Ni, Sb, Al, Pb and Sn (OR = 1.15; CI95% 1.06,1.25) and Mo and Co (OR = 0.56; CI95% 0.49,0.64). This is the first study that identified urinary metal mixtures that differed between women with and without BC. Our results warrant confirmation in further prospective epidemiological studies. In addition, the elucidation of underlying mechanisms of metal interactions on BC risk deserves further research.

Aluminum and tin: Food contamination and dietary intake in an Italian population.

Aluminum and tin are ubiquitous in the environment. In normal biological systems, however, they are present only in trace amounts and have no recognized biological functions in humans. High exposure to these metals can result in adverse health effects such as neurodegenerative diseases. In non-occupationally exposed subjects, diet is the primary source of exposure. In this study, we aimed at estimating dietary aluminum and tin intake in an Italian adult population. We measured aluminum and tin concentrations through inductively-coupled plasma mass spectrometry in 908 food samples. We also estimated dietary intake of these two metals, by using a validated semi-quantitative food-frequency questionnaire administered to 719 subjects (319 men and 400 women) recruited from the general population of the Emilia Romagna region, Northern Italy. We found the highest aluminum levels in legumes, sweets, and cereals, while the highest tin levels were in sweets, meat and seafood. The estimated median daily dietary intake of aluminum was 4.1 mg/day (Interquartile range - IQR: 3.3-5.2), with a major contribution from beverages (28.6%), cereals (16.9%), and leafy vegetables (15.2%). As for tin, we estimated a median intake of 66.8 µg/day (IQR: 46.7-93.7), with a major contribution from vegetables (mainly tomatoes) (24.9%), fruit (15.5%), aged cheese (12.2%), and processed meat (10.4%). This study provides an updated estimate of the dietary intake of aluminum and tin in a Northern-Italy adult population, based on data from a validated food-frequency questionnaire. The intake determined for this population does not exceed the established thresholds of tolerable intake.

[Determination of organo-tin residues in edible vegetable oil by positive chemical ionization-gas chromatography-mass spectrometry].

For the determination of organo-tin residues in edible vegetable oil, a method was developed based on gas chromatography-mass spectrometric (GC-MS) with positive chemical ionization (PCI). The edible oil samples were first dissolved by cyclohexane-ethyl acetate (1:1, v/v), and then purified by gel permeation chromatography (GPC). After derivatization by sodium tetraethylborate, the samples were analyzed by GC-MS with PCI source in the single ion monitor (SIM) mode. The seven organo-tin compounds showed good linear relationships in the range of 20-2000 µg/L and the correlation coefficients exceeded 0.99. The limits of quantitation (LOQs) and the average recoveries of the seven organo-tin compounds were 0.3-1.2 µg/kg and 66.2%-103.2%, respectively, and the relative standard deviations were less than 11.5% at three spike levels (0.05, 0.10, and 0.20 mg/kg). The method showed good linearity and high sensitivity and can be used for the determination of organo-tin residues in edible vegetable oil.

Spatial pattern of the environmental exposure to tin in the vicinity of an alloy industry in Volta Redonda, Rio de Janeiro State, Brazil / Padrão espacial da exposição ambiental ao estanho nos arredores de uma indústria de ligas metálicas em Volta Redonda, Estado do Rio de Janeiro, Brasil / Patrón espacial de exposición ambiental al estaño en las proximidades de una industria de aleación en Volta Redonda, estado de Río de Janeiro, Brasil

Abstract: Despite being widely used in industry, the literature on tin and its effects in humans is scarce, especially regarding reference values in biological indicators such as blood and urine. Similarly, environmental limits are also rare. This study sought to assess the spatial distribution of hotspots in the environmental exposure to tin in the vicinity of an alloy industry in the south region of the state of Rio de Janeiro, Brazil. The study population consisted of 74 adults. Graphite furnace atomic absorption spectrometry determined tin in all samples. Households and points around the industry were georeferenced with the use of GPS to identify the most intense tin sites. Results of the first and second campaigns ranged from 0.022 to 0.153 and 0.003 to 0.445µg m-3 for the atmospheric air, whereas such ranges were 0.64 to 1.61 and 1.97 to 8.54µg m-2 for household dust, respectively. The mean tin concentration found in the blood of the population was 3.85 ± 1.57µg L-1. In urine the value was 3.56 ± 1.88µg L-1. The kernel map showed the highest spatial concentrations of tin in household dust in the eastern region of the industry. In the first sampling, atmospheric air samples presented the most elevated concentrations in the southwest and southeast. Although the direction of the wind was northwest, potentially high risks were concentrated in the central area in the second collection. The largest hotspots were in the north, south and southeast regions; however, urine samples showed medium to high levels in the west and east regions. Regarding blood samples, the greatest difference was the absence of hotspot areas in the west. Environmental monitoring becomes necessary to better assess the exposure to tin.

Resumo: O estanho é amplamente utilizado na indústria. A literatura sobre seus efeitos em humanos é escassa, principalmente quanto aos valores de referência em indicadores biológicos como sangue e urina. Também são raros os estudos sobre os limites do estanho no meio ambiente. O estudo teve como objetivo avaliar os pontos críticos da distribuição espacial da exposição ambiental ao estanho nos arredores de uma indústria de ligas metálicas na região sul do Estado do Rio de Janeiro, Brasil. A população do estudo consistiu em 74 adultos. O estanho foi medido em todas as amostras com a espectrometria de absorção atômica em forno de grafite. As residências e outros pontos em torno da indústria foram georreferenciados com GPS para identificar os locais com maior concentração de estanho. Os resultados da primeira e segunda campanhas variaram entre 0,022 e 0,153 e entre 0,003 e 0,445µg m-3 para o ar atmosférico, enquanto para a poeira doméstica as faixas foram 0,64-1,61 e 1,97-8,54µg m-2, respectivamente. A concentração sanguínea média de estanho na população foi 385 ± 1,57µg L-1 e na urina foi 3,56 ± 1,88µg L-1. O mapa kernel mostrou as concentrações mais elevadas de estanho na poeira doméstica nos arredores ao leste da indústria. Na primeira amostragem, o ar atmosférico apresentou as concentrações ao sudoeste e sudeste da fábrica. Entretanto, riscos potencialmente altos estiveram concentrados na área central, embora a direção do vento tenha sido noroeste na segunda coleta de amostras. Os maiores pontos críticos foram ao norte, sul e sudeste da indústria, mas as amostras de urina mostraram níveis moderados a altos ao oeste a ao leste. Nas amostras de sangue, a maior diferença foi a ausência de pontos críticos ao oeste da indústria. O monitoramento ambiental é necessário para melhor avaliar a exposição ao estanho.

Resumen: El uso del estaño está muy generalizado en la industria. La literatura sobre sus efectos en humanos es escasa, especialmente en lo que concierne a los valores de referencia en indicadores biológicos como sangre y orina. Igualmente, los límites ambientales también son raros. El objetivo de este estudio fue evaluar los puntos calientes de la distribución espacial de exposición ambiental al estaño, en las proximidades de una industria de aleación, en el sur del estado de Río de Janeiro, Brasil. El estudio poblacional contó con 74 adultos. La espectrometría de absorción atómica por horno de grafito halló estaño en todas las muestras. Asimismo, las residencias se georreferenciaron con puntos alrededor de la industria mediante GPS para identificar los lugares con mayor intensidad de estaño. Los resultados de la primera y segunda campaña oscilaron de 0,022 a 0,153 y 0,003 a 0,445µg m-3 en aire atmosférico, aunque tales rangos fueron de 0,64 a 1,61 y de 1,97 a 8,54µg m-2 en el caso de polvo doméstico, respectivamente. El promedio de concentración de estaño encontrado en la sangre de la población fue 3.85 ± 1.57µg L-1. Respecto a la orina, este valor fue 3.56 ± 1.88µg L-1. El mapa de kernel expuso que las concentraciones espaciales más altas de estaño en el polvo doméstico de las casas se encontraron en la región oriental de la industria. En la primera muestra, las muestras de aire atmosférico presentaron las concentraciones más elevadas en el suroeste y sureste. No obstante, los riesgos potencialmente altos se concentraron en el área central, a pesar de que la dirección del viento era noroeste en la segunda recogida de muestras. Los puntos calientes más grandes estuvieron en el norte, sur, y sureste. Sin embargo, las muestras de orina mostraron niveles de medios a altos en el oeste y este. Respecto a las muestras de sangre, la diferencia más grande fue la ausencia de áreas calientes en el oeste. El monitoreo ambiental se hace necesario para evaluar mejor la exposición al estaño.

Development of a large volume injection method using a programmed temperature vaporization injector - gas chromatography hyphenated to ICP-MS for the simultaneous determination of mercury, tin and lead species at ultra-trace levels in natural waters.

The current EU legislation lays down Environmental Quality Standards (EQS) for 45 priority substances in surface waters; among them levels for (organo)metallic species of Hg, Sn and Pb are set between ng L-1 (for Hg and Sn) and µg L-1 (for Pb). To date, only a few analytical methods can reach these very restrictive limits and there is thus a need for comprehensive methods able to analyze these species down to these levels in natural waters. The aim of this work was to develop an online automated pre-concentration method using large volume injections with a Programmed Temperature Vaporization (PTV) injector fitted with a sorbent packed liner coupled to GC-ICP-MS to further improve the detection limits associated to this well-established method. The influence of several parameters such as the PTV transfer temperature and time, carrier gas flow rate and amount of packing material was investigated. Finally, the maximum volume injected through single or multiple injection modes was optimized to obtain the best compromise between chromatographic resolution and sensitivity. After optimization, very satisfactory results in terms of absolute and methodological detection limits were achieved, down to the pg L-1 level for all species studied. The potential of the method was exemplified by determining the concentrations of organometallic compounds in unpolluted river waters samples from the Adour river basin (SW France) and results were compared with conventional (splitless) GC-ICP-MS. The strength of this analytical method lies in the low detection limits reached for the simultaneous analysis of a wide group of organometallic compounds, and the potential to transfer this method to other gas chromatographic applications with inherent lower sensitivity.

Strategies to Reduce Tin and Other Metals in Electronic Cigarette Aerosol.

BACKGROUND: Metals are present in electronic cigarette (EC) fluid and aerosol and may present health risks to users. OBJECTIVE: The objective of this study was to measure the amounts of tin, copper, zinc, silver, nickel and chromium in the aerosol from four brands of EC and to identify the sources of these metals by examining the elemental composition of the atomizer components. METHODS: Four brands of popular EC were dissected and the cartomizers were examined microscopically. Elemental composition of cartomizer components was determined using integrated energy dispersive X-ray microanalysis, and the concentrations of the tin, copper, zinc silver, nickel, and chromium in the aerosol were determined for each brand using inductively coupled plasma optical emission spectroscopy. RESULTS: All filaments were made of nickel and chromium. Thick wires were copper coated with either tin or silver. Wires were joined to each other by tin solder, brazing, or by brass clamps. High concentrations of tin were detected in the aerosol when tin solder joints were friable. Tin coating on copper wires also contributed to tin in the aerosol. CONCLUSIONS: Tin concentrations in EC aerosols varied both within and between brands. Tin in aerosol was reduced by coating the thick wire with silver rather than tin, placing stable tin solder joints outside the atomizing chamber, joining wires with brass clamps or by brazing rather than soldering wires. These data demonstrate the feasibility of removing tin and other unwanted metals from EC aerosol by altering designs and using materials of suitable quality.

Dust metal loadings and the risk of childhood acute lymphoblastic leukemia.

We evaluated the relationship between the risk of childhood acute lymphoblastic leukemia (ALL) and the levels of metals in carpet dust. A dust sample was collected from the homes of 142 ALL cases and 187 controls participating in the California Childhood Leukemia Study using a high volume small surface sampler (2001-2006). Samples were analyzed using microwave-assisted acid digestion in combination with inductively coupled plasma mass spectrometry for arsenic, cadmium, chromium, copper, lead, nickel, tin, tungsten, and zinc. Eight metals were detected in at least 85% of the case and control homes; tungsten was detected in <15% of homes. Relationships between dust metal loadings (µg metal per m(2) carpet) and ALL risk were modeled using multivariable logistic regression, adjusting for the child's age, sex, and race/ethnicity and confounders, including household annual income. A doubling of dust metal loadings was not associated with significant changes in ALL risk (odds ratio (95% confidence interval): arsenic: 0.96 (0.86, 1.07), cadmium: 0.92 (0.81, 1.05), chromium: 1.01 (0.90, 1.14), copper: 0.97 (0.91, 1.03), lead: 1.01 (0.93, 1.10), nickel: 0.95 (0.82, 1.09), tin: 0.96 (0.86, 1.08), and zinc: 0.94 (0.84, 1.05)). Our findings do not support the hypothesis that metals in carpet dust are risk factors for childhood ALL.

Fluorescence turn-on detection of Sn2+ in live eukaryotic and prokaryotic cells.

Sn(2+) is usually added to toothpaste to prevent dental plaque and oral disease. However, studies of its physiological role and bacteriostatic mechanism are restricted by the lack of versatile Sn(2+) detection methods applicable to live cells, including Streptococcus mutans. Here we report two Sn(2+) fluorescent probes containing a rhodamine B derivative as a fluorophore, linked via the amide moiety to N,N-bis(2-hydroxyethyl)ethylenediamine (R1) and tert-butyl carbazate group (R2), respectively. These probes can selectively chelate Sn(2+) and show marked fluorescence enhancement due to the ring open reaction of rhodamine induced by Sn(2+) chelation. The probes have high sensitivity and selectivity for Sn(2+) in the presence of various relevant metal ions. Particularly, both R1 and R2 can target lysosomes, and R2 can probe Sn concentrations in lysosomes with rather acidic microenvironment. Furthermore, these two probes have low toxicity and can be used as imaging probes for monitoring Sn(2+) not only in live KB cells (eukaryotic) but also in Streptococcus mutans cells (prokaryotic), which is a useful tool to study the physiological function of Sn(2+) in biological systems.

Migration of iron, lead, cadmium and tin from tinplate-coated cans into chickpeas.

Migration studies of trace metals were carried out on coated chickpea cans marketed in Lebanon. Four elements--(Fe), tin (Sn), lead (Pb) and cadmium (Cd)--were analysed by atomic absorption spectrometry (AAS) after microwave digestion. Over 3 months, three different storage temperatures (5°C, room temperature and 40°C) were tested. In all cases, the migration of Fe reached a plateau after around 50 days of storage, while the migration of Pb was slow till 50 days, then it increased rapidly. Cd and Sn levels did not increase. Moreover, no effect of temperature was observed in the case of Fe, whereas Pb levels showed slower migration in cans stored at 5°C. Comparing cans from different chickpea brands (Lebanese and foreign) showed that the characteristics of the container have an effect on metal release.

Highly sensitive and selective rhodamine-based "off-on" reversible chemosensor for tin (Sn4+) and imaging in living cells.

A structurally characterized new oxo-chromene functionalized rhodamine derivative L1 exhibits high selectivity toward Sn(4+) by forming a 1:1 complex, among other biologically important metal ions, as studied by fluorescence, absorption, and HRMS spectroscopy. Complexing with Sn(4+) triggers the formation of a highly fluorescent ring-open form which is pink in color. The sensor shows extremely high fluorescence enhancement upon complexation with Sn(4+), and it can be used as a "naked-eye" sensor. DFT computational studies carried out in mimicking the formation of a 1:1 complex between L1 and Sn(4+) resulted in a nearly planar pentacoordinate Sn(IV) complex. Studies reveal that the in situ prepared L1-Sn complex is selectively and fully reversible in presence of sulfide anions. Further, confocal microscopic studies confirmed that the receptor shows in vitro detection of Sn(4+) ions in RAW cells.

Determination of toxic elements (mercury, cadmium, lead, tin and arsenic) in fish and shellfish samples. Risk assessment for the consumers.

Although fish intake has potential health benefits, the presence of metal contamination in seafood has raised public health concerns. In this study, levels of mercury, cadmium, lead, tin and arsenic have been determined in fresh, canned and frozen fish and shellfish products and compared with the maximum levels currently in force. In a further step, potential human health risks for the consumers were assessed. A total of 485 samples of the 43 most frequently consumed fish and shellfish species in Andalusia (Southern Spain) were analyzed for their toxic elements content. High mercury concentrations were found in some predatory species (blue shark, cat shark, swordfish and tuna), although they were below the regulatory maximum levels. In the case of cadmium, bivalve mollusks such as canned clams and mussels presented higher concentrations than fish, but almost none of the samples analyzed exceeded the maximum levels. Lead concentrations were almost negligible with the exception of frozen common sole, which showed median levels above the legal limit. Tin levels in canned products were far below the maximum regulatory limit, indicating that no significant tin was transferred from the can. Arsenic concentrations were higher in crustaceans such as fresh and frozen shrimps. The risk assessment performed indicated that fish and shellfish products were safe for the average consumer, although a potential risk cannot be dismissed for regular or excessive consumers of particular fish species, such as tuna, swordfish, blue shark and cat shark (for mercury) and common sole (for lead).

Relative radiological risks derived from different TENORM wastes in Malaysia.

In Malaysia technologically enhanced naturally occurring radioactive materials (TENORM) wastes are mainly the product of the oil and gas industry and mineral processing. Among these TENORM wastes are tin tailing, tin slag, gypsum and oil sludge. Mineral processing and oil and gas industries produce large volume of TENORM wastes that has become a radiological concern to the authorities. A study was carried out to assess the radiological risk related to workers working at these disposal sites and landfills as well as to the members of the public should these areas be developed for future land use. Radiological risk was assessed based on the magnitude of radiation hazard, effective dose rates and excess cancer risks. Effective dose rates and excess cancer risks were estimated using RESRAD 6.4 computer code. All data on the activity concentrations of NORM in wastes and sludges used in this study were obtained from the Atomic Energy Licensing Board, Malaysia, and they were collected over a period of between 5 and 10 y. Results obtained showed that there was a wide range in the total activity concentrations (TAC) of nuclides in the TENORM wastes. With the exception of tin slag and tin tailing-based TENORM wastes, all other TENORM wastes have TAC values comparable to that of Malaysia's soil. Occupational Effective Dose Rates estimated in all landfill areas were lower than the 20 mSv y(-1) permissible dose limit. The average Excess Cancer Risk Coefficient was estimated to be 2.77×10(-3) risk per mSv. The effective dose rates for residents living on gypsum and oil sludge-based TENORM wastes landfills were estimated to be lower than the permissible dose limit for members of the public, and was also comparable to that of the average Malaysia's ordinary soils. The average excess cancer risk coefficient was estimated to be 3.19×10(-3) risk per mSv. Results obtained suggest that gypsum and oil sludge-based TENORM wastes should be exempted from any radiological regulatory control and should be considered radiologically safe for future land use.

Análise de especiação de estanho em plasma de trabalhadores expostos / Speciation analysis of tin in plasma of exposed workers

O estanho (Sn) é um elemento natural na crosta terrestre obtido a partir do minério cassiterita. Devido à sua utilização em processos industriais, é encontrado distribuído pelo ambiente, e sendo um potencial contaminante. Na natureza, aparece nas formas inorgânicas e orgânicas, e quanto menor a cadeia orgânica associada ao metal, maior toxicidade do composto. Compostos organoestânicos de cadeia curta, como trimetil e trietil Sn, são bem absorvidos no trato gastrointestinal. Compostos organoestânicos podem penetrar nas membranas celulares, causando danos celulares e nas mitocôndrias, e ainda interromper a fosforilação oxidativa. Desta forma, podem ser imuno e genotóxicos. O interesse na especiação dos compostos de Sn é devido à toxicidade ser dependente da espécie. O plasma sanguíneo contém a fração biodisponível do analito e pode intermediar a predição de algumas formas de toxicidade crônica. No entanto, há poucos trabalhos sobre como o Sn se encontra no plasma. Portanto, a caracterização dos constituintes que se ligam e / ou transportam esse elemento ajustam na compreensão de seu metabolismo, elucidação dos mecanismos de toxicidade, uma melhor compreensão da distribuição de Sn na célula e sua de posição nos tecidos. Neste estudo, foi desenvolvido um método analítico para separação das espécies de Sn no plasma sanguíneo de trabalhadores que beneficiam o minério de cassiterita, através de cromatografia líquida por filtração em gel, enquanto a concentração do Sn nas frações coletadas foi determinada por espectrometria de absorção atômica por forno de grafite. O uso de Sepharose CL-4B, uma coluna com altura de 1 m, fase móvel de 50 milimolares (mM) Tris-HCl + 30 mM NaHCO3, pH 7,4, fluxo de 0,7 militros por minuto (ml min-1), volumes de plasma injetado e frações coletadas iguais a 2 ml cada,apresentou melhor separação das proteínas, com o aparecimento de três picos...

Tin is a natural element in the earth's crust and is obtained from cassiterite ores. Owing to their wide use in industrial processes, tin is relatively distributed in the environment. In nature, it occurs in both inorganic and organic forms and shorter organic chainassociated to the metal, higher the toxicity of the compound. Short-chain organotin compounds such as trimethyl and triethyl tin are well absorbed in the gastrointestinal tract. Organotin compounds can penetrate cell membranes causing damage to cell andmitochondria, as well as interrupt oxidative phosphorylation. Thus organic compounds can be immunotoxic and genotoxic. The interest on speciation of the organotin compounds is due to species-dependent toxicity. The blood plasma contains the bioavailable fraction of the analyte and can mediate the prediction of some forms ofchronic toxicity. However, very few species of tin existing in the plasma are known. Therefore, the characterization of the constituents that bind to and / or transporting the element of interest is critical to full understanding of metabolism, elucidation of themechanisms of toxicity, a better understanding of the distribution of tin in the cell and its deposition in tissues. In this study, we developed an analytical method for theseparation of tin species in blood plasma using gel filtration liquid chromatography while tin concentration in the collected fractions was determined by graphite furnace atomic absorption spectrometry. The use of Sepharose CL-4B, height of 1 m, mobilephase of 50mM Tris-HCl + 30mM NaHCO3, pH 7,4, flow 0,7 ml min-1, fractions collected volume of 2 ml, plasma injected volume of 2 ml, showed the best protein separation with three peaks. For the determination of tin, pyrolisis and atomization...

Optimisation of a headspace-solid-phase micro-extraction method for simultaneous determination of organometallic compounds of mercury, lead and tin in water by gas chromatography-tandem mass spectrometry.

In this work, a headspace-solid-phase micro-extraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) method for multielemental speciation of organometallic compounds of mercury, lead and tin in water samples was upgraded by the introduction of tandem mass spectrometry (MS/MS) as detection technique. The analytical method is based on the ethylation with NaBEt(4) and simultaneous headspace-solid-phase micro-extraction of the derivative compounds followed by GC-MS/MS analysis. The main experimental parameters influencing the extraction efficiency such as derivatisation time, extraction time and extraction temperature were optimized. The overall optimum extraction conditions were the following: a 50 microm/30 microm divinyl-benzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) SPME fibre, 150 min derivatisation time, 15 min extraction time, sample agitation at 250 rpm and 40 degrees C extraction temperature. The analytical characteristics of the HS-SPME method combined with GC-MS and GC-MS/MS were evaluated. The combination of both techniques HS-SPME and GC-MS/MS allowed to attain lower limits of detection (4-33 ng l(-1)) than those obtained by HS-SPME-GC-MS (17-45 ng l(-1)). The proposed method presented good linear regression coefficients (r(2)>0.9970) and repeatability (4.8-21.0%) for all the compounds under study. The accuracy of the method measured as the average percentage recovery of the compounds in spiked river water and seawater samples was higher than 80% for all the compounds studied, except for monobutyltin in the river water sample. A study of the uncertainty associated with the analytical results was also carried out.

Graphite furnace and hydride generation atomic absorption spectrometric determination of cadmium, lead, and tin traces in natural surface waters: study of preconcentration technique performance.

In this study three major types of preconcentration methods based upon different principles (cation exchange, physical absorption and hydrophobic extraction) were evaluated and optimized for the extraction and determination of three highly toxic heavy metals namely Cd, Pb and Sn by graphite furnace and hybrid generation atomic absorption spectrometry in real samples. The optimum analytical conditions were examined and the analytical features of each method were revealed and compared. Detection limits as low as 0.003-0.025 microg L(-1) for Cd(2+), 0.05-0.10 microg L(-1) for Pb(2+) and 0.1-0.25 microg L(-1) for Sn(4+) depending on the extraction method were obtained with RSD values between 3.08% and 6.11%. A preliminary assessment of the pollution status of three important natural ecosystems in Epirus region (NW Greece) was performed and some early conclusions were drawn and discussed.