Scheelite weathering and tungsten (W) mobility in historical oxidic-sulfidic skarn tailings at Yxsjöberg, Sweden.

More knowledge of the geochemical behavior of tungsten (W) and associated contamination risks is needed. Therefore, weathering of scheelite (CaWO4) and secondary sequestration and transport of W to groundwater in historical skarn tailings and surface water downstream of the tailings were studied. The tailings contained 920 mg/kg W, primarily in scheelite. Mineralogical and geochemical analyses were combined to elucidate the geochemical behavior of W in the tailings, and water samples were taken monthly during 2018 to monitor its mobility. In the tailings, a large peak of W was found at 1.5 m depth. There, 30 wt%. of W was present in easily reducible phases, indicating former scheelite weathering. Currently, W is being released from scheelite to water-soluble phases at 2.5 m depth. The release of WO42- is hypothetically attributed to anion exchange with CO32- released from calcite neutralizing acid produced from pyrrhotite oxidation in the upper tailings and transported downwards to pH conditions > 7. Higher concentrations of dissolved W were found in the groundwater and particulate W in downstream surface water than in reference water, but they were lower than current contamination thresholds. Tungsten showed correlations with hydrous ferric oxides (HFO) in both the tailings and surface water.

High Resolution Physical Characterization of Single Metallic Nanoparticles.

Individual molecules can be detected and characterized by measuring the degree by which they reduce the ionic current flowing through a single nanometer-scale pore. The signal is characteristic of the molecule's physicochemical properties and its interactions with the pore. We demonstrate that the nanopore formed by the bacterial protein exotoxin Staphylococcus aureus alpha hemolysin (αHL) can detect polyoxometalates (POMs, anionic metal oxygen clusters), at the single molecule limit. Moreover, multiple degradation products of 12-phosphotungstic acid POM (PTA, H3PW12O40) in solution are simultaneously measured. The single molecule sensitivity of the nanopore method allows for POMs to be characterized at significantly lower concentrations than required for nuclear magnetic resonance (NMR) spectroscopy. This technique could serve as a new tool for chemists to study the molecular properties of polyoxometalates or other metallic clusters, to better understand POM synthetic processes, and possibly improve their yield. Hypothetically, the location of a given atom, or the rotation of a fragment in the molecule, and the metal oxidation state could be investigated with this method. In addition, this new technique has the advantage of allowing the real-time monitoring of molecules in solution.

Arsenic migration during co-processing of secondary residues from ammonium paratungstate production in cement kiln.

To reduce the environmental pollution caused by ammonium paratungstate (APT) production in the Ganzhou area in China, simulated experiments in laboratory and field experiments in cement kilns were performed. The migration characteristics of As in secondary residues (thermometallurgy and hydrometallurgy residues) from APT production in cement kilns were similar, and As in the residues existed in the form of sulfides. When the residues were fed at the kiln inlet, the As in the residues was completely distributed in the clinker after a new mass balance of As was reestablished in a very short time. When the residues were fed at the raw mill, the total input rate of As was far higher than the total output rate. Therefore, a part of As was circulated in the cement kiln, and only a small part of As was distributed in the clinker. In addition, the As concentration in the flue gas and the leaching concentration of As in the clinker were far below the limit value in the Chinese standard. For feeding rates below that are used in the field experiment, co-processing of secondary residues in a cement kiln fed at the kiln inlet is environmentally safe. However, if the secondary residues are consistently fed at the raw mill, the As concentration in the flue gas may gradually increase.

Tungstate removal from aqueous solution by nanocrystalline iowaite: An iron-bearing layered double hydroxide.

Tungstate enrichment in aquatic systems may cause negative environmental and health effects. This study addresses tungstate removal from aqueous solution by nanocrystalline iowaite, an iron-bearing layered double hydroxide, which has not been used for treatment of tungstate-rich waters so far. Tungstate sorption experiments were conducted with various contact times, temperatures, initial tungstate concentrations (0.001-2 mM), and solution pH values (2-13), the results indicating that iowaite sorbed aqueous tungstate effectively and quickly, and the sorption maximum can be up to 71.9 mg/g. Moreover, the tungsten sorption capacity keeps nearly constant at a wide pH range from 3 to 11. Duo to its pH buffering effect, the alkaline conditions were generated by the addition of iowaite, which are favorable for the removal of aqueous tungstate because the polymerization of tungstate can be prohibited at alkaline pH values. Zeta potential, XRD and XPS analyses were employed to clarify the sorption mechanisms, and it was concluded that tungstate was sorbed via its exchange with the chloride originally intercalated into iowaite interlayers as well as its stronger inner-sphere complexation with the Fe atoms located in iowaite layers. Nanocrystalline iowaite is suitable for treating both tungstate-bearing natural waters with moderately high tungstate concentrations and industrial wastewaters extremely rich in tungstate.

Tungstate adsorption onto Italian soils with different characteristics.

The study of tungsten in the environment is currently of considerable interest because of the growing concerns resulting from its possible toxicity and carcinogenicity. Adsorption reactions are some of the fundamental processes governing the fate and transport of tungsten compounds in soil. This paper reports data on the adsorption of tungstate ions in three different Italian soils, which are characteristic of the Mediterranean region. The results show that pH is the most important factor governing the adsorption of tungstate in these soils. The data interpreted according to the Langmuir equation show that the maximum value of adsorption is approximately 30 mmol kg-1 for the most acidic soil (pH = 4.50) and approximately 9 mmol kg-1 for the most basic soil (pH = 7.40). In addition, soil organic matter is shown to play a fundamental role in adsorption processes, which are favored in soils with a higher organic matter content. The data could contribute to a better understanding of the behavior of tungsten compounds in Italian soils for which current knowledge is very scarce, also in view of environmental regulations, which are currently lacking.

Nanoparticles of WC-Co, WC, Co and Cu of relevance for traffic wear particles - Particle stability and reactivity in synthetic surface water and influence of humic matter.

Studded tyres made of tungsten carbide cobalt (WC-Co) are in the Northern countries commonly used during the winter time. Tungsten (W)-containing nano- and micron-sized particles have been detected close to busy roads in several European countries. Other typical traffic wear particles consist of copper (Cu). The aims of this study were to investigate particle stability and transformation/dissolution properties of nanoparticles (NPs) of WC-Co compared with NPs of tungsten carbide (WC), cobalt (Co), and Cu. Their physicochemical characteristics (primarily surface oxide and charge) are compared with their extent of sedimentation and metal release in synthetic surface water (SW) with and without two different model organic molecules, 2,3- and 3,4-dihydroxybenzoic acid (DHBA) mimicking certain sorption sites of humic substances, for time periods up to 22 days. The WC-Co NPs possessed a higher electrochemical and chemical reactivity in SW with and without DHBA molecules as compared with NPs of WC, Co, and Cu. Co was completely released from the WC-Co NPs within a few hours of exposure, although it remained adsorbed/bonded to the particle surface and enabled the adsorption of negatively charged DHBA molecules, in contrast with the WC NPs (no adsorption of DHBA). The DHBA molecules were found to rapidly adsorb on the Co and Cu NPs. The sedimentation of the WC and WC-Co NPs was not influenced by the presence of the 2,3- or 3,4-DHBA molecules. A slight influence (slower sedimentation) was observed for the Co NPs, and a strong influence (slower sedimentation) was observed for the Cu NPs in SW with 2,3-DHBA compared with SW alone. The extent of metal release increased in the order: WC < Cu < Co < WC-Co NPs. All NPs released more than 1 wt-% of their metal total mass. The release from the Cu NPs was most influenced by the presence of DHBA molecules.

Tungstate (VI) sorption on hematite: An in situ ATR-FTIR probe on the mechanism.

Owing to the suspected toxicity and carcinogenicity of tungstate (VI) oxyanions [i.e. mono tungstate and several polytungstate, generally represented by W (VI)], the environmental fate of W (VI) has been widely studied. Sorption is regarded as a major mechanism by which W (VI) species are retained in the solid/water interface. Iron (hydr)oxides have been considered important environmental sinks for W (VI) species. Here we report sorption mechanisms of W (VI) on a common iron oxide mineral-hematite under environmentally relevant solution properties using in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopic probes. Initial W (VI) loadings varied from 10 to 200 µM at fixed pH values ranged from 4.6 to 8.1. For pH envelop (pHs = 4.6, 5.0, 5.5, 6.0, 6.5, 7.5, and 8.1) experiments, fixed W (VI) concentrations (i.e. 10 & 200 µM) were used to understand the effects of pH. The results indicated that at acidic pH values (pH < 6.0) the sorbed polytungstate surface species are prominent at 200 µM initial W (VI) conc. The pH envelop experiments revealed that sorbed polytungstates can be present even at lower initial W (VI) conc. (i.e. 10 µM) at pH values <5.5. Overall, our in situ ATR-FTIR experiments indicated that W (VI) forms inner-sphere type bonds on hematite surface and the strength of the interaction increases with decreasing pH. In addition, initial W (VI) concentration affected the sorption mechanisms of W (VI) on hematite. Our study will aid the molecular level understanding of W (VI) retention on iron oxide surfaces.

Characterization of Protein Aggregating Tungstates: Electrospray Mass Spectrometry Analysis of Extracts from Prefilled Syringes and from Tungsten Pins Used in the Manufacture of Syringes.

UNLABELLED: Glass prefilled syringes are increasingly becoming a container of choice for storing and administering therapeutic protein products to patients. Tungsten leaching from a PFS is known to induce protein particle formation, and the source was traced to the tungsten pins used in the manufacturing process of the syringe barrels. Study of the tungstates present in extracts from both tungsten pins used in the syringe manufacturing process and from single syringes from various suppliers was undertaken. Electrospray mass spectrometry was chosen as a technique with the sensitivity to characterize tungstates at levels (∼1 ppm of elemental tungsten) observed in single syringes. Extraction solvents were chosen to simulate the range (pH 4.0-7.0) typically used for therapeutic protein formulation. A commercial product formulation buffer was also used as an extraction solution to characterize tungstate species used for tungsten spiking studies of protein. All pin and syringe extracts from various manufacturers were similar in regards to containing stable Na/K containing lacunary polytungstate ([W11O39](7-)) species, which were the main species present in syringe extracts and are different than the metatungstate ([W12O39](6-)) species identified in commercially available sodium polytungstate and as the main species in pin extracts. These stable Na/K containing polytungstates species present in pin and syringe extracts are likely formed during the glass manufacturing process at >400 °C and may have the capability to subsequently form larger polytungstate complexes. LAY ABSTRACT: Glass prefilled syringes are a type of container used for storing and administering biotechnology medicines to patients. The manufacturing process for the syringes may lead to very low levels of the metal tungsten being present in the syringes, and thus in the medicine stored in the syringes. The presence of tungsten in certain biotechnology medicines has been shown to cause changes to the medicine. Understanding something that can cause a medicine to change is an important part of producing safe and effective medicines for patients. The study described in this article sought to increase understanding by characterizing the form of tungsten observed in syringes from a number of vendors. Study of the tungsten present in syringes from four vendors indicates the same form of tungsten is observed regardless of the vendor. The study also found that the form of tungsten differed from that expected.

Simultaneous speciation analysis of chromate, molybdate, tungstate and vanadate in welding fume alkaline extracts by HPLC-ICP-MS.

A novel analytical procedure was developed for the simultaneous speciation analysis of chromate, molybdate, tungstate and vanadate by anion-exchange high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Linear gradient elution from 100% water to 100% 0.7 M NaCl was applied for chromatographic separation of metal species. In standard aqueous solution at neutral pH molybdate, tungstate and vanadate exist in several aqueous species, while chromate is present as a single CrO4(2-) species. Consequently, only chromate can be separated from this solution in a sharp chromatographic peak. For obtaining sharp chromatographic peaks for molybdate, tungstate and vanadate, the pH of aqueous standard solutions was raised to 12. At highly alkaline conditions single CrO4(2-), MoO4(2-) and WO4(2-) are present and were eluted in sharp chromatographic peaks, while VO4(3-) species, which predominates at pH 12 was eluted in slightly broaden peak. In a mixture of aqueous standard solutions (pH 12) chromate, molybdate, tungstate and vanadate were eluted at retention times from 380 to 420 s, 320 to 370 s, 300 to 350 s and 240 to 360 s, respectively. Eluted species were simultaneously detected on-line by ICP-MS recording m/z 52, 95, 182 and 51. The developed procedure was successfully applied to the analysis of leachable concentrations of chromate, molybdate, tungstate and vanadate in alkaline extracts (2% NaOH+3% Na2CO3) of manual metal arc (MMA) welding fumes loaded on filters. Good repeatability and reproducibility of measurement (RSD±3.0%) for the investigated species were obtained in both aqueous standard solutions (pH 12) and in alkaline extracts of welding fumes. Low limits of detection (LODs) were found for chromate (0.02 ng Cr mL(-1)), molybdate (0.1 ng Mo mL(-1)), tungstate (0.1 ng W mL(-1)) and vanadate (0.2 ng V mL(-1)). The accuracy of analytical procedure for the determination of chromate was checked by analysis of CRM 545, Cr(VI) in welding dust loaded on a filter. Good agreement between determined and reported certified values was obtained. For molybdate, tungstate and vanadate the assessment of accuracy was performed by spiking welding fume filters. Good recoveries for all investigated species (98-101%) confirmed the accuracy of the analytical procedure.

Influence of composition on setting kinetics of new injectable and/or fast setting tricalcium silicate cements.

OBJECTIVES: New commercial tricalcium silicate based cements were elaborated to improve handling properties and setting time. The goals of the present work were: (i) to determine the composition of the new injectable and/or fast setting calcium silicate based cements, and (ii) to investigate the impact of the differences in composition on their setting kinetics. METHODS: The materials considered were Angelus MTA™, Biodentine™, MM-MTA™, MTA-Caps™, and ProRoot MTA™ as control. Elemental composition of materials was studied by Inductively Coupled Plasma-Atomic Emission Spectroscopy and X-ray Energy Dispersive analysis, whereas phases in presence were analyzed by Micro-Raman spectroscopy and X-ray Diffraction analysis and cement surface by Scanning Electron Microscope. Setting kinetics was evaluated using rheometry. RESULTS: Elemental analysis revealed, for all cements, the presence of three major components: calcium, silicon and oxygen. Chlorine was detected in MM-MTA, MTA-Caps and Biodentine. Different radio-opacifiers were identified: bismuth oxide in ProRoot MTA, Angelus MTA and MM-MTA, zirconium oxide in Biodentine and calcium tungstate (CaWO4) in MTA-Caps. All cements were composed of di- and tri-calcium silicate, except Biodentine for which only the latter was detected. Major differences in setting kinetics were observed: a modulus of 8×10(8)Pa is reached after 12min for Biodentine, 150min for MM-MTA, 230min for Angelus MTA and 320min for ProRoot MTA. The maximum modulus reached by MTA-Caps was 7×10(8)Pa after 150min. SIGNIFICANCE: Even if these cements possess some common compounds, major differences in their composition were observed between them, which directly influence their setting kinetics.

Elemental analysis of occupational and environmental lung diseases by electron probe microanalyzer with wavelength dispersive spectrometer.

Occupational and environmental lung diseases are a group of pulmonary disorders caused by inhalation of harmful particles, mists, vapors or gases. Mineralogical analysis is not generally required in the diagnosis of most cases of these diseases. Apart from minerals that are encountered rarely or only in specific occupations, small quantities of mineral dusts are present in the healthy lung. As such when mineralogical analysis is required, quantitative or semi-quantitative methods must be employed. An electron probe microanalyzer with wavelength dispersive spectrometer (EPMA-WDS) enables analysis of human lung tissue for deposits of elements by both qualitative and semi-quantitative methods. Since 1993, we have analyzed 162 cases of suspected occupational and environmental lung diseases using an EPMA-WDS. Our institute has been accepting online requests for elemental analysis of lung tissue samples by EPMA-WDS since January 2011. Hard metal lung disease is an occupational interstitial lung disease that primarily affects workers exposed to the dust of tungsten carbide. The characteristic pathological findings of the disease are giant cell interstitial pneumonia (GIP) with centrilobular fibrosis, surrounded by mild alveolitis with giant cells within the alveolar space. EPMA-WDS analysis of biopsied lung tissue from patients with GIP has demonstrated that tungsten and/or cobalt is distributed in the giant cells and centrilobular fibrosing lesion in GIP. Pneumoconiosis, caused by amorphous silica, and acute interstitial pneumonia, associated with the giant tsunami, were also elementally analyzed by EPMA-WDS. The results suggest that commonly found elements, such as silicon, aluminum, and iron, may cause occupational and environmental lung diseases.

Tungsten toxicity, bioaccumulation, and compartmentalization into organisms representing two trophic levels.

Metallic tungsten has civil and military applications and was considered a green alternative to lead. Recent reports of contamination in drinking water and soil have raised scrutiny and suspended some applications. This investigation employed the cabbage Brassica oleracae and snail Otala lactea as models to determine the toxicological implications of sodium tungstate and an aged tungsten powder-spiked soil containing monomeric and polymeric tungstates. Aged soil bioassays indicated cabbage growth was impaired at 436 mg of W/kg, while snail survival was not impacted up to 3793 mg of W/kg. In a dermal exposure, sodium tungstate was more toxic to the snail, with a lethal median concentration of 859 mg of W/kg. While the snail significantly bioaccumulated tungsten, predominately in the hepatopancreas, cabbage leaves bioaccumulated much higher concentrations. Synchrotron-based mapping indicated the highest levels of W were in the veins of cabbage leaves. Our results suggest snails consuming contaminated cabbage accumulated higher tungsten concentrations relative to the concentrations directly bioaccumulated from soil, indicating the importance of robust trophic transfer investigations. Finally, synchrotron mapping provided evidence of tungsten in the inner layer of the snail shell, suggesting potential use of snail shells as a biomonitoring tool for metal contamination.

Resonance Rayleigh scattering spectra, non-linear scattering spectra of malachite green-12-tungstophosphoric acid system and its analytical application in fish.

In 0.1 molL(-1) (pH 1.0) HCl medium, 12-tungstophosphoric acid (TP) reacted with malachite green (MG) to form an ion-association complex. As a result, the new spectra of RRS, SOS and FDS appeared and their intensities were enhanced greatly. The maximum wavelengths of RRS, SOS and FDS were located at 334 nm, 586 nm and 330 nm, and the scattering intensities were proportional to the concentration of MG. Based on it a new method for the determination of MG has been established. The detection limits (3σ) of these methods were in the range of 3.7-27 ng mL(-1). The RRS, SOS, and FDS characteristics, absorption spectrum characteristics and optimum reaction conditions of the system were discussed. Effects of coexistent substances were tested, and the results demonstrated that this method had good selectivity. It has been applied to the determination of malachite green residues in fish flesh with satisfactory results. The reaction mechanism and reasons of RRS enhancement are discussed.

Lead and copper in pigeons (Columbia livia) exposed to a small arms-range soil.

Small arms-range (SAR) soils can be contaminated with metals from spent copper (Cu)-jacketed bullets. Avian species are particularly at risk because they are exposed to lead (Pb) through ingestion of grit, soil intake from preening, or ingestion of contaminated food near ranges. Examination of the effects of Pb on birds at ranges have mainly focused on intake and toxicity of Pb shot pellets or fragments; however, Pb in soils may be an important pathway of exposure. To evaluate the uptake and effects of Pb from an actual range, the soil fraction (<250 µm) from a contaminated SAR soil was used to dose pigeons (Columbia livia) for 14 days at low (2700 µg Pb and 215 µg Cu/d) and high (5400 µg Pb and 430 µg Cu/d) doses. At the end of the study, blood Pb and erythrocyte protoporphyrin were determined, and tissues were analyzed for Pb and Cu. Results showed that Pb was absorbed in a dose-response manner in blood, tissues, and feathers, and erythrocyte protoporphyrin, a biomarker of early Pb effect, was increased at blood Pb levels >50 µg/dL. Four tissues showed differential retention of Pb, with kidney having the highest concentration followed by liver, brain, and heart, whereas Cu levels were not changed. To examine possible interactions with other metals, amendments of either Cu or tungstate were made to the soil sample. Although these amendments seemed to decrease the absorption of Pb, the results were ambiguous compared with sodium chloride controls. Overall, this study showed that intake of SAR soils contaminated with Pb and Cu causes an increase in Pb body burdens in birds and that the response can be modulated by amending soils with salts of metals.

Tungsten speciation and toxicity: acute toxicity of mono- and poly-tungstates to fish.

Tungsten is a widely used transition metal for which very limited information on environmental and toxicological effects is available. Of particular interest is the lack of information linking tungsten speciation and environmental effects. Tungsten anions may polymerize (depending upon concentration, pH, and aquatic geochemistry) in aquatic and soil systems. However, to this date, of all soluble tungstate species only monotungstates have been scrutinized to a fair extent in toxicological studies. The objective of this work is a comparative assessment of the acute toxicity of monotungstates (sodium tungstate, Na(2)WO(4)) and polytungstates (sodium metatungstate, 3Na(2)WO(4).9WO(3)) to Poecilia reticulate. The experiments have been performed according to the OEDC protocols 203 and 204. LD50 values for 1-14 days show that sodium metatungstate is significantly more toxic to fish than sodium tungstate. Based on LD50 (0.86-3.88gL(-1) or 4.67-21.1x10(-3)molNa(2)WO(4)L(-1)), sodium tungstate may be classified as a chemical of low toxicity to fish. Sodium metatungstate caused similar fish mortality to sodium tungstate when it was introduced in 55-80 times lower concentrations (in terms of molL(-1)) than sodium tungstate. LD50 values for sodium metatungstate range from 0.13 to 0.85gWL(-1) or 5.69 to 38.71x10(-5)mol 3Na(2)WO(4).9WO(3)L(-1). Based on these values sodium metatungstate can be classified as a moderate toxic agent to fish.

Investigations of tungsten mobility in soil using column tests.

The geochemistry of tungsten has recently gained attention in the scientific and regulatory communities. Tungsten has a complex geochemistry, existing in many environmental matrices as the soluble and mobile tungstate anion, as well as a series of ill-defined polymeric species. Previous work has shown that soluble tungsten leached from a metallic tungsten-spiked Grenada Loring soil will reach an equilibrium concentration >150 mgL(-1), and the concentration is greatly influenced by co-occurring analytes in the matrix, such as calcium and phosphate. In the present work, the mobility of tungsten compounds was investigated in a model soil with a range of aqueous leach solutions using column experiments. The relative column leachate concentrations measured followed trends from previously reported tungstate and polytungstate partition coefficients determined in the model soil under identical aqueous matrix conditions. Neutral to alkaline conditions produced maximum effluent tungsten concentrations >40 mgL(-1), whereas acid leach eluents produced concentrations in the <1-3 mgL(-1) range. The change in leached tungsten speciation over time was also measured as monomeric and polymeric tungsten species have different sorptive behaviors.

Comparison between exhaled breath condensate analysis as a marker for cobalt and tungsten exposure and biomonitoring in workers of a hard metal alloy processing plant.

OBJECTIVE: Cobalt (Co), Tungsten (W) and Tungsten Carbides (WC) are major constituents of hard metal alloys. Whereas little is known about potential health hazards due to tungsten carbide exposure, occupational exposure to cobalt has been shown to induce a variety of respiratory diseases. Since the concentration of a potentially hazardous substance in the target organ is the most meaningful risk indicator in occupational medicine, the detection of hard metals in exhaled breath condensate (EBC) has been proposed to be a valuable instrument. The present study examines the correlation of Co and W concentrations in EBC and urine with one another and various spirometrical and clinical parameters to scrutinize this potential. METHODS: A total of 62 subjects (90.3% males, age 40.6 +/- 9.2 years) were recruited from a hard metal processing plant in Germany. Examinations included the airborne workplace exposure, a complete spirometry, measurements of Co and W concentrations in EBC and urine with high resolution inductive coupled plasma mass spectrometry (HR ICP-MS) and graphite furnace atomic absorption spectrometry (GFAAS). RESULTS: Air concentrations ranged between 0.0019 mg/m(3) and 0.074 mg/m(3) for Co and 0.012 mg/m(3) and 0.021 mg/m(3) for W. Median urine concentrations and interquartile ranges of the exposed subjects ranged from 0.81 (0.0-1.46) microg/l for Co and 30.5 (14.5-57.7) microg/l for W. Median breath condensate metal concentrations and interquartile ranges ranged from 8.4 (5.0-13.9) microg/l for Co and 8.8 (4.4-18.5) microg/l for W. Urine concentrations of Co and W were closely related to the airborne workplace exposure that had been assessed by air monitoring. EBC concentrations of Co and W showed no correlations to urinary W and Co concentrations and the ambient monitoring results of the individual workplace, respectively. Cobalt EBC concentration was elevated in subjects who reported to have suffered from respiratory disease; both Co and W concentrations in EBC, however, decreased with increasing spirometrical signs of obstruction. CONCLUSION: According to our study, urinary concentrations of Co and W seem to be more reliable indicators of current workplace exposure than EBC concentrations. As far as new methods and exposure matrices for valid concentration measurements in respiratory organs and possible hazardous effects--especially of cobalt--in the lung are concerned, the present results are less clear-cut, and further research is required.

[Preparation and spectrum of multilayer films of polyoxometalate {(Eu(PW11)2)m/PEI}].

The layer-by-layer assembly (LBL) is a new method of thin film deposition often used for oppositely charged polyelectrolytes. LBL technique has been extensively used to make multilayer films of polyions with biomolecules such as proteins, enzymes and DNA. It can also be successfully applied to the preparation of thin films of nanoparticles. Ultrathin multilayer films containing a polyoxometalate (Eu(PW11)2)m and PEI were prepared using layer-by-layer assembly method in the present work. The stable multilayer films were assembled by alternate adsorption of negatively charged POM and positively charged polyelectrolytes from their aqueous dispersions. The growth of the multilayer films is regular. The proposed novel immobilized method exhibited good stability and the photoluminescent behavior of films at room temperature was investigated to show the Eu3+ characteristic emission pattern, which is important for practical application.

[Preparation and luminescence properties of Tb3+ ion and Na2WO4 co-doped SiO2 materials].

Tb3+ and Na2 WO4 co-doped SiO2 materials were prepared by sol-gel method and the structure of materials were measured by DTA-TG, IR and XRD techniques. The results indicate that the materials were in amorphous phase andthe Si-O-Si bond was still observed in samples annealed at 800 degrees C. The influence of Na2 WO4 on luminescence properties of terbium glasses was investigated by three-dimension fluorescence spectra, excitation and emission spectra. It is approve that when sample excited by 230 nm showed the characteristic emission peaks of terbium corresponding to 5D4-(7) Fj (j = 4, 5, 6) and 5 D3 -(7)Fj (j = 4, 5, 6) transitions. Doping Na2 WO4 has less influence with the emission position of SiO2 materials with terbium, but has a great effect with the emission intensity. It is find that the blue transition of 5D4-7F6 was activated and the green transition of 5D4-7F5 was quenched and the materials radiate green blue fluorescence light under ultraviolet light. The mechanism of sample was analyzed by the energy levels of Tb3+ and Na2 WO4 co-doped glasses.

Determination of verapamil hydrochloride with 12-tungstophosphoric acid by resonance Rayleigh scattering method coupled to flow injection system.

A flow injection analysis (FIA) method coupled to resonance Rayleigh scattering (RRS) detection for the determination of verapamil hydrochloride (VP) was proposed. In pH 1.0 acidic medium, 12-tungstophosphoric acid (TP) reacted with VP to form an ion-association complex, which resulted in a significant enhancement of RRS intensity. The maximum scattering peak was located at 293 nm. RRS intensity was proportional to the concentration of VP in the range of 0.017-13.0 microg mL(-1), and the detection limit (3sigma) was 5.1 ng mL(-1). The proposed method exhibited satisfactory reproducibility with a relative standard derivation (R.S.D.) of 2.1% for 11 successive determinations of 5.0 microg mL(-1) VP. Therefore, a novel method for the determination of VP by FIA-RRS was developed. The optimum reaction conditions and the parameters of the FIA operation such as flow rate, injection volume, reactor length, and so on had been optimized in this paper. The present method had been applied to the determination of VP in serum samples and pharmaceuticals with satisfactory results. The maximal sample throughput in the optimized system was 80 h(-1).