Mercury determination in various environmental, food and material complex matrices using unified operating conditions for a cold vapor generation high-resolution continuum source quartz tube atomic absorption spectrometry method.

An analytical method with broad applicability based on cold vapor generation high-resolution continuum source quartz tube atomic absorption spectrometry was developed and evaluated for the determination of total mercury in matrices with various complexities and compositions. Sample preparation for different matrices of food, environmental samples and (bio)polymeric materials and unified operating conditions for derivatization and measurement were evaluated. The method was validated according to established requirements (Eurachem Guide 2014, EC Decisions 657/2002; 333/2007; 836/2011 and Association of Official Analytical Chemists Guide - AOAC). Analytical versatility was checked on various samples of fish fillets, mushrooms, soil, water and water sediment, sludge from a wastewater treatment unit, and (bio)polymeric materials from waste recycled from food packaging, computers and garden tools. Under optimal conditions for cold vapor generation in a batch system, namely 3% (v/v) HCl as reaction medium for 5 mL aliquot samples and a volume of 3.5 mL 0.3% (m/v) NaBH4 stabilized in 0.2% (m/v) NaOH as derivatization reagent, the detection limit for Hg in terms of peak height measurement (n = 7 days) was in the range 0.064 ± 0.004 µg L-1 in water, 0.014 ± 0.001 mg kg-1 in environmental samples and 0.009 ± 0.001 mg kg-1 in (bio)polymeric materials. Overall recovery of Hg by analysis of certified reference materials was 102 ± 20% (k = 2) in food, soil, wastewater and water sediment, and polyethylene. Precision for the measurement of various real samples ranged between 4.2 and 15.0%. A performance study highlighted that the method was sensitive, free of non-spectral interference coming from the multielemental matrix and that it complied with the requirements for Hg determination set in EC Decisions and AOAC Guidelines at least for the more common matrices analyzed for social impact.

Assessment of mercury bioavailability in garden soils around a former nonferrous metal mining area using DGT, accumulation in vegetables, and implications for health risk.

Mercury (Hg) is a toxic, non-essential element for living organisms, frequently present in high concentrations in soils from industrial areas. The total, dissolved, and labile Hg concentrations in garden soils and their accumulation in edible vegetables (onion, garlic, lettuce, and parsley) grown on contaminated soils in localities situated a former mining area were evaluated. The labile Hg fraction was estimated by diffusive gradient in thin films (DGT). The soil-to-vegetable transfer factors, as well as the health risk by exposure to Hg, were calculated based on the labile Hg concentration in soil. The total Hg concentration in soil varied widely (0.11-3.77 mg kg-1), Hg in soil solution ranged between 2.14 and 20.2 µg L-1 and labile Hg between 1.13 and 18.6 µg L-1. About 36-96% (84% on average) of the Hg concentration in soil solution was found in labile form. Multivariate analysis revealed significant correlations between the labile Hg concentration in soil and Hg accumulated in vegetables. The hazard indices showed that, although the study area is affected by legacy pollution, exposure to soil and consumption of locally grown vegetables do not pose health risks.

In-situ Diffusive Gradients in thin-films passive sampling coupled with ex-situ small-sized electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry as green and white method for the simultaneous determination of labile species of toxic elements in surface water.

This study presents for the first time the coupling between in-situ Diffusive Gradient in Thin-film (DGT) passive sampling technique and ex-situ small-sized instrumentation based on electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry (SSETV-µCCP-OES) for the simultaneous determination of Cd, Pb, Cu, Zn and Hg in surface water. Unique features of the DGT-SSETV-µCCP-OES are low power and low Ar consumption for plasma generation (15 W, 150 mL min-1) and significant improvement of the detection limits following DGT passive sampling. The new method was validated in terms of river water analysis in comparison with graphite furnace atomic absorption spectrometry and thermal decomposition atomic absorption spectrometry. Combining the abilities of preconcentration by in-situ Chelex-DGT passive sampling with plasma microtorch equipped with a low resolution microspectrometer provided multielemental simultaneous determination with detection limits of (µg L-1) 0.01 (Cd, Zn and Hg), 0.02 (Cu) and 0.07 (Pb) in water, at least one order of magnitude better than using grab sampling without preconcentration. It was possible the quantification of labile fraction of priority hazardous metals (Cd, Pb) in river water below the instrumental limits of detection (µg L-1) of 0.12 and 0.80 obtained in SSETV-µCCP-OES without DGT sampling. The precision of the method was in the range 15.3-22.4% (combined uncertainty), while the accuracy was 95-103% and trueness of 27-33% (expanded uncertainty, k = 2). The DGT-SSETV-µCCP-OES coupling proved to be an ideal and powerful tool for surface water analysis in compliance with green and white analytical chemistry concepts. The application of the RGB-12 algorithm provided very good red/green (AGREEprep)/blue/white scores (%) of 100/80/98/93, determined primarily by in-situ DGT passive sampling, very good detection limits and cost-effective SSETV-µCCP-OES instrumentation.

Unified analysis method for total and inorganic As determination in foodstuffs by hydride generation high-resolution continuum source quartz tube atomic absorption spectrometry.

A unified analytical method applicable to common foodstuff matrices was developed and characterized for total and inorganic arsenic determination by hydride generation high-resolution continuum source quartz tube atomic absorption spectrometry, which was established based on different sample preparation procedures. This new method was found to be interference-free and cost-effective in terms of reagents consumption for sample preparation and derivatization to arsine for the inorganic arsenic fraction. Microwave-assisted digestion in HNO3-H2O2 for total arsenic and extraction in 0.28 mol L-1 HNO3 by mechanical stirring in a water bath or ultrasound-assisted extraction in 0.01 mol L-1 HCl without separation of inorganic As, all coupled with arsine generation in 0.01 mol L-1 HCl medium with 0.6% NaBH4 in 0.01% NaOH in the presence of 0.2% L-cysteine was found to be suitable for all matrices. The results were statistically compared by applying Tukey's and Dunnett's multiple comparison methods (p > 0.05). The use of external calibration with As(III) standards and standard addition method for quantification showed the lack of non-spectral interferences from the multimineral matrices, resulting in a reliable method for total/inorganic As determination in various foodstuffs. The limits of detection for total/inorganic As using peak height measurement were 0.0044 ± 0.0005/0.0022 ± 0.0003 mg kg-1 (n = 25 days). The overall recovery for total/inorganic As in the certified reference materials was in the range of 98% ± 22%, and 99% ± 24% (k = 2). The extraction of inorganic As in 0.01 mol L-1 HCl and 0.28 mol L-1 HNO3 provided the recovery of 106% ± 25% and 100% ± 25% (k = 2), which was better than in 10 mol L-1 HCl. The precision of measurements in real samples of fish muscle, meat and organs, rice and rice-based baby foods with contents of 0.052-5.29 mg kg-1 total As and 0.005-0.063 mg kg-1 inorganic As was 9.8-18.8% and 8.7-32.0%, respectively, which was calculated based on the combined uncertainty.

Magnetic and Magnetocaloric Properties of Nano- and Polycrystalline Manganites La(0.7-x)EuxBa0.3MnO3.

Here, we report synthesis and investigations of bulk and nano-sized La(0.7-x)EuxBa0.3MnO3 (x ≤ 0.4) compounds. The study presents a comparison between the structural and magnetic properties of the nano- and polycrystalline manganites La(0.7-x)EuxBa0.3MnO3, which are potential magnetocaloric materials to be used in domestic magnetic refrigeration close to room temperature. The parent compound, La0.7Ba0.3MnO3, has Curie temperature TC = 340 K. The magnetocaloric effect is at its maximum around TC. To reduce this temperature below 300 K, we partially replaced the La ions with Eu ions. A solid-state reaction was used to prepare bulk polycrystalline materials, and a sol-gel method was used for the nanoparticles. X-ray diffraction was used for the structural characterization of the compounds. Transmission electron spectroscopy (TEM) evidenced nanoparticle sizes in the range of 40-80 nm. Iodometry and inductively coupled plasma optical emission spectrometry (ICP-OES) was used to investigate the oxygen content of the studied compounds. Critical exponents were calculated for all samples, with bulk samples being governed by tricritical mean field model and nanocrystalline samples governed by the 3D Heisenberg model. The bulk sample with x = 0.05 shows room temperature phase transition TC = 297 K, which decreases with increasing x for the other samples. All nano-sized compounds show lower TC values compared to the same bulk samples. The magnetocaloric effect in bulk samples revealed a greater magnetic entropy change in a relatively narrow temperature range, while nanoparticles show lower values, but in a temperature range several times larger. The relative cooling power for bulk and nano-sized samples exhibit approximately equal values for the same substitution level, and this fact can substantially contribute to applications in magnetic refrigeration near room temperature. By combining the magnetic properties of the nano- and polycrystalline manganites, better magnetocaloric materials can be obtained.

Effect of in vitro simulated gastrointestinal digestion on some nutritional characteristics of several dried fruits.

To provide new information on potential health benefits of dried fruits, the effects of in vitro digestion on minerals, total phenolics, total sugars and the antioxidant capacities were evaluated. For the first time, the bioaccessibility of these compounds during in vitro digestion was assessed by multivariate statistical analysis. Although the amount of all minerals decreased after digestion, moderate bioaccessibility was found, excepting Zn. The highest bioaccessibility of phenolics was obtained in prunes and the lowest in dates and cranberries. Total sugars content increased after in vitro digestion of dates, raisins and coconut, but decreased for cranberries, prunes and banana. The in vitro digestion led to an increase in the antioxidant capacity for the majority of dried fruits. The similarities/dis-similarities in pattern of analyzed parameters during digestion was revealed by heat map. Two-way joining cluster and principal component analysis were used to highlight the most relevant parameters in each digestion phase.

Application of Inductively Coupled Plasma Spectrometric Techniques and Multivariate Statistical Analysis in the Hydrogeochemical Profiling of Caves-Case Study Cloșani, Romania.

The aim of the study was to develop the hydrogeochemical profiling of caves based on the elemental composition of water and silty soil samples and a multivariate statistical analysis. Major and trace elements, including rare earths, were determined in the water and soil samples. The general characteristics of water, anions content, inorganic and organic carbon fractions and nitrogen species (NO3- and NH4+) were also considered. The ANOVA-principal component analysis (PCA) and two-way joining analysis were applied on samples collected from Cloșani Cave, Romania. The ANOVA-PCA revealed that the hydrogeochemical characteristics of Ca2+-HCO3- water facies were described by five factors, the strongest being associated with water-carbonate rock interactions and the occurrence of Ca, Mg and HCO3- (43.4%). Although organic carbon fractions have a lower influence (20.1%) than inorganic ones on water characteristics, they are involved in the chemical processes of nitrogen and of the elements involved in redox processes (Fe, Mn, Cr and Sn). The seasonal variability of water characteristics, especially during the spring, was observed. The variability of silty soil samples was described by four principal components, the strongest influence being attributed to rare earth elements (52.2%). The ANOVA-PCA provided deeper information compared to Gibbs and Piper diagrams and the correlation analysis.

Simultaneous Determination of As, Bi, Sb, Se, Te, Hg, Pb and Sn by Small-Sized Electrothermal Vaporization Capacitively Coupled Plasma Microtorch Optical Emission Spectrometry Using Direct Liquid Microsampling.

The simultaneous determination of chemical vapor-generating elements involving derivatization is difficult even by inductively coupled plasma optical emission spectrometry or mass spectrometry. This study proposes a new direct liquid microsampling method for the simultaneous determination of As, Bi, Se, Te, Hg, Pb, and Sn, using a fully miniaturized set-up based on electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry. The method is cost-effective, free from non-spectral interference, and easy to run by avoiding derivatization. The method involves the vaporization of analytes from the 10 µL sample and recording of episodic spectra generated in low-power (15 W) and low-Ar consumption (150 mL min-1) plasma microtorch interfaced with low-resolution microspectrometers. Selective vaporization at 1300 °C ensured the avoidance of non-spectral effects and allowed the use of external calibration. Several spectral lines for each element even in the range 180-210 nm could be selected. Generally, this spectral range is examined with large-scale instrumentation. Even in the absence of derivatization, the obtained detection limits were low (0.02-0.75 mg kg-1) and allowed analysis of environmental samples, such as cave and river sediments. The recovery was in the range of 86-116%, and the accuracy was better than 10%. The method is of general interest and could be implemented on any miniaturized or classical laboratory spectrometric instrumentation.

Interference-free, green microanalytical method for total mercury and methylmercury determination in biological and environmental samples using small-sized electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry.

An analytical method for the quantification of total Hg and CH3Hg+ in biological tissues (fish, mushroom) and water sediment was developed based on small-sized electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry using a low-resolution microspectrometer as detector. Sample preparation was carried out according to the procedure recommended by JRC Technical Report of European Commission for the determination of CH3Hg+ in seafood and adapted by us for lower consumption of reagents. Amounts of 0.1 - 0.5 g sample were subjected to extraction in 5 ml of 47% HBr then CH3Hg+ was extracted in 2 × 1 ml toluene and back-extracted in 2 ml aqueous solution of 1% l-cysteine. Total Hg/CH3Hg+ were quantified in 10 µl of acidic extract/l-cysteine solution after electrothermal vaporization and measurement of 253.652 nm Hg signal in the episodic emission spectra. Under the optimal working conditions of system (70 °C sample drying, 1300 °C sample vaporization, 10 W plasma power and 150 ml min-1 Ar flow) the limits of detection were 7.0 µg kg-1 total Hg and 3.5 µg kg-1 CH3Hg+. Comparison of slopes in external calibration and standard addition procedure revealed the lack of non-spectral interferences of multimineral matrix, so that the calibration against Hg2+ standards was adopted. Pooled recovery of total mercury/methylmercury was 101 ± 7%/100 ± 7%, while precision assessed from measurements of real samples was in the range 1.6-9.6%/2.7-12.8%. The proposed method validated according to Eurachem Guide 2014 is selective and complies with demands in European legislation (Decisions 657/2002; 333/2007; 836/2011) and Association of Official Analytical Chemists Guide in terms of performances for food control. The method displays a high degree of greenness by circumventing cold vapor generation, use of small amounts of reagents and full-miniaturized instrumentation resulting in low analytical costs without reducing results quality. Besides, the method is simple and rapid, since it uses external calibration curves prepared from Hg2+standard solutions both for total Hg and CH3Hg+ determination.

Influence of Mixed Additives on the Physicochemical Properties of a 5.25% Sodium Hypochlorite Solution: An Unsupervised Multivariate Statistical Approach.

INTRODUCTION: This article reports for the first time the effects of multiple additives (polyethylene glycol 400, Triton X-100, benzalkonium chloride, and ethyl formate) on the surface tension, pH, and viscosity of 5.25% sodium hypochlorite (NaOCl) irrigant solution. Advanced statistical approaches based on unsupervised multivariate analysis (cluster analysis and principal component analysis) were used to quantify the variability of the physicochemical properties of the modified NaOCl solution for the first time in dentistry. METHODS: Solutions of 5.25% NaOCl were modified with multiple additives in various concentrations, physicochemical parameters were measured at 22°C and 37°C, and the results were statistically analyzed to group the solutions and reveal the effects of additives. RESULTS: Cluster analysis and principal component analysis revealed that pH and surface tension were the significant parameters (P < .05) for grouping the modified solutions. Four principal components, accounting for 90.6% of the total variance, were associated with flow characteristics (37.3%) determined by polyethylene glycol; the wetting property (22.5% and 10.5%), which was dependent on cationic and nonionic surfactant; and the antimicrobial effect (20.3%) influenced by ethyl formate. Varimax rotation of the principal components showed that the cationic surfactant (benzalkonium chloride) had significantly decreased surface tension compared with the nonionic surfactant (Triton-X). Although ethyl formate was introduced as an odor modifier, it had a significant effect on pH decrease and the occurrence of effervescence with O2 and hypochlorous acid release. CONCLUSIONS: The statistical results revealed that the 5.25% NaOCl irrigant solution should be modified with a mixture of 0.1% benzalkonium chloride, 1% ethyl formate, and 7% polyethylene glycol for obtaining a low pH and low surface tension.

Methylmercury determination in seafood by photochemical vapor generation capacitively coupled plasma microtorch optical emission spectrometry.

A non-chromatographic method based on double liquid-liquid extraction and measurements by UV photochemical vapor generation capacitively coupled plasma microtorch optical emission spectrometry was developed and characterized for methylmercury determination in seafood. Samples were prepared following the procedure recommended in JRC Technical Report of European Commission formerly proposed for the determination of methylmercury in seafood by thermal decomposition atomic absorption spectrometry, namely confinement of Hg species in 47% HBr solution, extraction of CH3Hg+ in toluene and back-extraction in 1% l-cysteine aqueous solution. Mercury cold vapor was generated by flow injection UV photo-reduction from CH3Hg+ in 0.6molL-1 HCOOH, while quantification was performed against external Hg2+ aqueous standards and measuring Hg 253.652nm emission using a low power/Ar consumption plasma microtorch (15W, 100mLmin-1) and a low resolution microspectrometer (Ocean Optics). The figures of merit and analytical capability were assessed by analyzing certified reference materials and test samples of fish fillet and discussed in relation with requirements for Hg determination in seafood in European legislation (Decisions 2007/333/EC and 2002/657/EC) as well as compared to performances achieved in thermal decomposition atomic absorption spectrometry. The limit of detection and quantification of 2µgkg-1 and 6µgkg-1 respectively, precision of 2.7-9.4% and accuracy of 99±8% of the proposed method for the determination of CH3Hg+ fulfill the demands of European legislation for Hg quantification. The limit of detection and quantification were better than those in the used reference method or other non-/chromatographic methods taken for comparison. The analysis of certified reference materials and the Bland and Altman test performed on 12 test samples confirmed trueness of the proposed method and its reliability for the determination of traces of CH3Hg+ with 95% confidence level. The proposed method fulfills several demands of the eco-scale concept, is sensitive, simple and safe related to sample preparation through elimination of classical, harmful reductants and attractive by using economical miniaturized instrumentation incorporating a low power and low Ar consumption plasma.

Chemical modeling of groundwater in the Banat Plain, southwestern Romania, with elevated As content and co-occurring species by combining diagrams and unsupervised multivariate statistical approaches.

The study proposes a combined model based on diagrams (Gibbs, Piper, Stuyfzand Hydrogeochemical Classification System) and unsupervised statistical approaches (Cluster Analysis, Principal Component Analysis, Fuzzy Principal Component Analysis, Fuzzy Hierarchical Cross-Clustering) to describe natural enrichment of inorganic arsenic and co-occurring species in groundwater in the Banat Plain, southwestern Romania. Speciation of inorganic As (arsenite, arsenate), ion concentrations (Na+, K+, Ca2+, Mg2+, HCO3-, Cl-, F-, SO42-, PO43-, NO3-), pH, redox potential, conductivity and total dissolved substances were performed. Classical diagrams provided the hydrochemical characterization, while statistical approaches were helpful to establish (i) the mechanism of naturally occurring of As and F- species and the anthropogenic one for NO3-, SO42-, PO43- and K+ and (ii) classification of groundwater based on content of arsenic species. The HCO3- type of local groundwater and alkaline pH (8.31-8.49) were found to be responsible for the enrichment of arsenic species and occurrence of F- but by different paths. The PO43--AsO43- ion exchange, water-rock interaction (silicates hydrolysis and desorption from clay) were associated to arsenate enrichment in the oxidizing aquifer. Fuzzy Hierarchical Cross-Clustering was the strongest tool for the rapid simultaneous classification of groundwaters as a function of arsenic content and hydrogeochemical characteristics. The approach indicated the Na+-F--pH cluster as marker for groundwater with naturally elevated As and highlighted which parameters need to be monitored. A chemical conceptual model illustrating the natural and anthropogenic paths and enrichment of As and co-occurring species in the local groundwater supported by mineralogical analysis of rocks was established.

Prediction of the fate of Hg and other contaminants in soil around a former chlor-alkali plant using Fuzzy Hierarchical Cross-Clustering approach.

An associative simultaneous fuzzy divisive hierarchical algorithm was used to predict the fate of Hg and other contaminants in soil around a former chlor-alkali plant. The algorithm was applied on several natural and anthropogenic characteristics of soil including water leachable, mobile, semi-mobile, non-mobile fractions and total Hg, Al, Ba, Ca, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Sr, Zn, water leachable fraction of Cl(-), NO3(-) and SO4(2)(-), pH and total organic carbon. The cross-classification algorithm provided a divisive fuzzy partition of the soil samples and associated characteristics. Soils outside the perimeter of the former chlor-alkali plant were clustered based on the natural characteristics and total Hg. In contaminated zones Hg speciation becomes relevant and the assessment of species distribution is necessary. The descending order of concentration of Hg species in the test site was semi-mobile>mobile>non-mobile>water-leachable. Physico-chemical features responsible for similarities or differences between uncontaminated soil samples or contaminated with Hg, Cu, Zn, Ba and NO3(-) were also highlighted. Other characteristics of the contaminated soil were found to be Ca, sulfate, Na and chloride, some of which with influence on Hg fate. The presence of Ca and sulfate in soil induced a higher water leachability of Hg, while Cu had an opposite effect by forming amalgam. The used algorithm provided an in-deep understanding of processes involving Hg species and allowed to make prediction of the fate of Hg and contaminants linked to chlor-alkali-industry.

A miniaturized capacitively coupled plasma microtorch optical emission spectrometer and a Rh coiled-filament as small-sized electrothermal vaporization device for simultaneous determination of volatile elements from liquid microsamples: spectral and analytical characterization.

A low power and low argon consumption (13.56 MHz, 15 W, 150 ml min(-1)) capacitively coupled plasma microtorch interfaced with a low-resolution microspectrometer and a small-sized electrothermal vaporization Rh coiled-filament as liquid microsample introduction device into the plasma was investigated for the simultaneous determination of several volatile elements of interest for environment. Constructive details, spectral and analytical characteristics, and optimum operating conditions of the laboratory equipment for the simultaneous determination of Ag, Cd, Cu, Pb and Zn requiring low vaporization power are provided. The method involves drying of 10 µl sample at 100°C, vaporization at 1500°C and emission measurement by capture of 20 successive spectral episodes each at an integration time of 500 ms. Experiments showed that emission of elements and plasma background were disturbed by the presence of complex matrix and hot Ar flow transporting the microsample into plasma. The emission spectrum of elements is simple, dominated by the resonance lines. The analytical system provided detection limits in the ng ml(-1) range: 0.5(Ag); 1.5(Cd); 5.6(Cu); 20(Pb) and 3(Zn) and absolute detection limits of the order of pg: 5(Ag); 15(Cd); 56(Cu); 200(Pb) and 30(Zn). It was demonstrated the utility and capability of the miniaturized analytical system in the simultaneous determination of elements in soil and water sediment using the standard addition method to compensate for the non-spectral effects of alkali and earth alkaline elements. The analysis of eight certified reference materials exhibited reliable results with recovery in the range of 95-108% and precision of 0.5-9.0% for the five examined elements. The proposed miniaturized analytical system is attractive due to the simple construction of the electrothermal vaporization device and microtorch, low costs associated to plasma generation, high analytical sensitivity and easy-to-run for simultaneous multielemental analysis of liquid microsamples.

Determination, speciation and distribution of mercury in soil in the surroundings of a former chlor-alkali plant: assessment of sequential extraction procedure and analytical technique.

BACKGROUND: The paper presents the evaluation of soil contamination with total, water-available, mobile, semi-mobile and non-mobile Hg fractions in the surroundings of a former chlor-alkali plant in connection with several chemical soil characteristics. Principal Component Analysis and Cluster Analysis were used to evaluate the chemical composition variability of soil and factors influencing the fate of Hg in such areas. The sequential extraction EPA 3200-Method and the determination technique based on capacitively coupled microplasma optical emission spectrometry were checked. RESULTS: A case study was conducted in the Turda town, Romania. The results revealed a high contamination with Hg in the area of the former chlor-alkali plant and waste landfills, where soils were categorized as hazardous waste. The weight of the Hg fractions decreased in the order semi-mobile > non-mobile > mobile > water leachable. Principal Component Analysis revealed 7 factors describing chemical composition variability of soil, of which 3 attributed to Hg species. Total Hg, semi-mobile, non-mobile and mobile fractions were observed to have a strong influence, while the water leachable fraction a weak influence. The two-dimensional plot of PCs highlighted 3 groups of sites according to the Hg contamination factor. The statistical approach has shown that the Hg fate in soil is dependent on pH, content of organic matter, Ca, Fe, Mn, Cu and SO42- rather than natural components, such as aluminosilicates. Cluster analysis of soil characteristics revealed 3 clusters, one of which including Hg species. Soil contamination with Cu as sulfate and Zn as nitrate was also observed. CONCLUSIONS: The approach based on speciation and statistical interpretation of data developed in this study could be useful in the investigation of other chlor-alkali contaminated areas. According to the Bland and Altman test the 3-step sequential extraction scheme is suitable for Hg speciation in soil, while the used determination method of Hg is appropriate.

Simple and robust method for lithium traces determination in drinking water by atomic emission using low-power capacitively coupled plasma microtorch and microspectrometer.

A method for Li determination in drinking water using atomic emission spectrometry in a new low-power Ar capacitively coupled plasma microtorch (15 W, 0.6 L min(-1)) with a detection limit of 0.013 µg L(-1) was developed. The method is based on external calibration in the presence of a buffering solution containing 5 mg L(-1) Na, K, Ca, Mg added both to calibration standards and water samples. The statistical validation on 31 bottled drinking water samples (0.4-2140 µg L(-1) Li) using the Bland and Altman test and regression analysis has shown results similar to those obtained by the standard additions method. The buffering solution approach is simpler than the standard additions and has demonstrated good intra- and interday precision, accuracy and robustness. It was successfully applied over a wide concentration range of Li and multimineral matrix with a pooled precision of 2.5-3.5% and 99±9% accuracy.

Arsenic and antimony determination in non- and biodegradable materials by hydride generation capacitively coupled plasma microtorch optical emission spectrometry.

A sensitive method using a miniature analytical system with a capacitively coupled plasma microtorch (25 W, 13.56 MHz, 0.4 l min(-1) Ar) was developed and evaluated for the determination of As and Sb in recyclable plastics and biodegradable materials by hydride generation optical emission spectrometry. Given their toxicity, As and Sb should be subject to monitoring in such materials despite not being included within the scope of Restriction of Hazardous Substances Directive. The advantages of the proposed approach are better detection limits and lower analysis cost relative to conventional systems based on inductively coupled plasma optical emission and flame atomic absorption spectrometry with/without derivatization. Samples were subjected to acidic microwave-assisted digestion in a nitric-sulfuric acid mixture. Chemical hydride generation with 0.5% NaBH4 after the prereduction of As(V) and Sb(V) with 0.3% L-cysteine in 0.01 mol l(-1) HCl (10 min contact time at 90±5°C) was used. Under the optimal hydride generation conditions and analytical system operation the detection limits (mg kg(-1)) were 0.5 (As) and 0.1 (Sb), whereas the precision was 0.4-7.1% for 10.2-46.2 mg kg(-1) As and 0.4-3.2% for 7.1-156 mg kg(-1) Sb. Analysis of two polyethylene CRMs revealed recoveries of 101±2% As and 100±1% Sb.

Validation of an analytical method based on the high-resolution continuum source flame atomic absorption spectrometry for the fast-sequential determination of several hazardous/priority hazardous metals in soil.

BACKGROUND: The aim of this paper was the validation of a new analytical method based on the high-resolution continuum source flame atomic absorption spectrometry for the fast-sequential determination of several hazardous/priority hazardous metals (Ag, Cd, Co, Cr, Cu, Ni, Pb and Zn) in soil after microwave assisted digestion in aqua regia. Determinations were performed on the ContrAA 300 (Analytik Jena) air-acetylene flame spectrometer equipped with xenon short-arc lamp as a continuum radiation source for all elements, double monochromator consisting of a prism pre-monocromator and an echelle grating monochromator, and charge coupled device as detector. For validation a method-performance study was conducted involving the establishment of the analytical performance of the new method (limits of detection and quantification, precision and accuracy). Moreover, the Bland and Altman statistical method was used in analyzing the agreement between the proposed assay and inductively coupled plasma optical emission spectrometry as standardized method for the multielemental determination in soil. RESULTS: The limits of detection in soil sample (3σ criterion) in the high-resolution continuum source flame atomic absorption spectrometry method were (mg/kg): 0.18 (Ag), 0.14 (Cd), 0.36 (Co), 0.25 (Cr), 0.09 (Cu), 1.0 (Ni), 1.4 (Pb) and 0.18 (Zn), close to those in inductively coupled plasma optical emission spectrometry: 0.12 (Ag), 0.05 (Cd), 0.15 (Co), 1.4 (Cr), 0.15 (Cu), 2.5 (Ni), 2.5 (Pb) and 0.04 (Zn). Accuracy was checked by analyzing 4 certified reference materials and a good agreement for 95% confidence interval was found in both methods, with recoveries in the range of 94-106% in atomic absorption and 97-103% in optical emission. Repeatability found by analyzing real soil samples was in the range 1.6-5.2% in atomic absorption, similar with that of 1.9-6.1% in optical emission spectrometry. The Bland and Altman method showed no statistical significant difference between the two spectrometric methods for 95% confidence interval. CONCLUSIONS: High-resolution continuum source flame atomic absorption spectrometry can be successfully used for the rapid, multielemental determination of hazardous/priority hazardous metals in soil with similar analytical performances to those in inductively coupled plasma optical emission spectrometry.

Characterization and assessment of potential environmental risk of tailings stored in seven impoundments in the Aries river basin, Western Romania.

BACKGROUND: The objective of this study was to examine the potential environmental risk of tailings resulted after precious and base metal ores processing, stored in seven impoundments located in the Aries river basin, Romania. The tailings were characterized by mineralogical and elemental composition, contamination indices, acid rock drainage generation potential and water leachability of hazardous/priority hazardous metals and ions. Multivariate statistical methods were used for data interpretation. RESULTS: Tailings were found to be highly contaminated with several hazardous/priority hazardous metals (As, Cu, Cd, Pb), and pose potential contamination risk for soil, sediments, surface and groundwater. Two out of the seven studied impoundments does not satisfy the criteria required for inert wastes, shows acid rock drainage potential and thus can contaminate the surface and groundwater. Three impoundments were found to be highly contaminated with As, Pb and Cd, two with As and other two with Cu. The tailings impoundments were grouped based on the enrichment factor, geoaccumulation index, contamination factor and contamination degree of 7 hazardous/priority hazardous metals (As, Cd, Cr, Cu, Ni, Pb, Zn) considered typical for the studied tailings. Principal component analysis showed that 47% of the elemental variability was attributable to alkaline silicate rocks, 31% to acidic S-containing minerals, 12% to carbonate minerals and 5% to biogenic elements. Leachability of metals and ions was ascribed in proportion of 61% to silicates, 11% to acidic minerals and 6% to the organic matter. A variability of 18% was attributed to leachability of biogenic elements (Na, K, Cl-, NO3-) with no potential environmental risk. Pattern recognition by agglomerative hierarchical clustering emphasized the grouping of impoundments in agreement with their contamination degree and acid rock drainage generation potential. CONCLUSIONS: Tailings stored in the studied impoundments were found to be contaminated with some hazardous/ priority hazardous metals, fluoride and sulphate and thus presents different contamination risk for the environment. A long term monitoring program of these tailings impoundments and the expansion of the ecologization measures in the area is required.

Magnesium and selenium in diabetics with peripheral artery disease of the lower limbs.

BACKGROUND AND AIMS: Knowing that diabetes mellitus (DM) often leads to cardiovascular injury such as peripheral artery disease (PAD) of the lower limbs and that some microelements like magnesium (Mg) and Selenium (Se) might be involved in the alterations entailed by these complications, we aimed to investigate the behavior of those microelements in these diseases. METHODS: We studied 114 patients with type 2 DM, treated not with insulin but only by diet or oral antidiabetics, mean aged 56.6 having a mean duration of the diabetes of 14.5 years, mostly men (80), 64 of them (40 men) having also PAD stage 2 without severe complications. We had a control group of 40 similarly-aged subjects without DM or PAD. The measurements were performed on a Konelab 30I device and serum selenium was quantified by atomic absorption spectroscopy. All patients underwent clinical, paraclinical and arterial Doppler echography for establishing the diagnosis of PAD. RESULTS: The results for controls were 2.2±0.4 mg/dl for Mg, 130±6 µg/dl for Se; diabetics had 1.68±0.4 mg/dl Mg, 88±6 µg/dl Se; diabetics with PAD had significantly lower levels: 1.36±0.6 mg/dl Mg, 66±6 µg/dl Se (p<0.05). Age inversely correlated with the values of both microelements especially in women. Mixed dysipidemia, present in DM, correlated with PAD. Blood pressure also inversely correlated with Mg and Se. Coronary heart disease (ischemia) linked to lower blood values of Mg and Se. Left Ventricle Hypertrophy (as proved by echography) also correlated to lower blood values of Mg and Se, as did glycated hemoglobin (HbA1c). CONCLUSION: We may conclude that in DM there is a Mg deficit which becomes significant in DZ+PAD especially in forms with high blood pressure (HBP), severe dyslipidemia and in the presence of early microvascular complications, our paper suggesting the opportunity of a substitutive treatment with Mg and Se in selected cases.