Einfluß der chemischen Bindung auf die Lα1,2− und Lβ1− Röntgenemissionsspektren des Arsens

The As Lα_1,2 and Lβ₁ X-ray emission spectra from metallic arsenic and from the compounds As₂O₃, Na₂HAsO₄·7H₂O, and GaAs were measured with high resolution and fluorescence excitation. The shape of the spectra and correlation between the chemical shifts of the Lα lines (0·1, ? 0·22 and ? 0·05 eV in As₂O₃, Na₂HAsO₄·7H₂O, and GaAs resp.) and atomic charges are discussed.     

Arsenic distribution in rats fed a Hijiki diet

Very large doses of sodium arsenate (Na₂HAsO₄), 14 mg As kg^?1 of body weight, were administered to Sprague-Dawley male rats (body weight 300 g) fed a 5% Hijiki diet by stomach tube twice within two days. After 24 h, the rats were sacrificed and various organs were dried for subsequent neutron activation analysis. The distribution of arsenic (As) in selected organs was determined by neutron activation analysis. The highest concentration of As was found in blood cells with a rather high concentration in the liver and heart. As the control, rats which were fed on a 5% cellulose diet were used. Control rats which were administered arsenate showed that the arsenic distribution and the concentration in their organs were similar to those on the 5% Hijiki diet. Even the blood cells of the controls without any arsenic administration were found to contain a small amount of arsenic.     

Biomethylation of arsenic and its excretion by the alga Chlorella vulgaris

Experimental results in this paper lead to the following conclusions. (1) Cell homogenates of Chlorella vulgaris adsorbed the inorganic arsenic compound Na₂HAsO₄ but no methylation of the arsenic occurred in vitro. (2) A small part of the arsenic bioaccumulated by C. vulgaris was methylated in vivo. The quantity of arsenic methylated in the cell increased with an increase of arsenic concentration in the medium. (3) When the arsenic-accumulating cells were transferred into arsenic-free media, the arsenic was excreted and the relative quantity of the methylated arsenic in the excrement was larger than that in the cell. (4) In the growth phase of C. vulgaris, a small fraction of the arsenic accumulated in the cell was first transformed to monomethyl and dimethyl-arsenic compounds during the early exponential phase, and after a short time a fraction was transformed to trimethylarsenic species.     

Comparative chronic toxicity,including tumorigenicity,of gallium arsenide and arsenic trioxide intratracheally instilled into hamsters

Chronic toxicity, including tumorigenicity, of gallium arsenide (GaAs) and arsenic trioxide (As₂O₃) were studied using Syrian golden hamsters given intermittent intratracheal instillations. GaAs particles (0.25 mg × 15 times/animal) were likely to produce relatively severe lung damage and the survival of the animals was shortened significantly compared with a control group. The tumor incidence of each group examined was GaAs (3.3%), As₂O₃ (3.3%) respectively, at a dose of 3.75 mg total metal given during 15 weeks. In this experiment, both arsenic trioxide and gallium arsenide had no apparent carcinogenicity or tumorigenicity.     

Interaction of arsenic and selenium on the metabolism of these elements in hamsters

The interaction of arsenic and selenium compounds on the metabolism of these elements in golden hamsters was studied. Golden hamsters were divided into three groups and administered sodium selenite (Na₂SeO₃), sodium arsenite (NaAsO₂) and Na₂SeO₃ with NaAsO₂, respectively, by a single Subcutaneous injection of 25 m?mol kg^?1 body weight as As or Se (arsenic and selenium were calculated as weight of elemental arsenic and selenium). Selenium and arsenic metabolites were determined by high-performance liquid chromatography–graphite furnace atomic absorption spectrometry (HPLC–GFA AA) and gas chromatography (GC). The results show (1): About 10% by weight of the given dose of selenium was excreted in expiration air as dimethylselenide (Me₂Se) during 12 h after administration of Na₂SeO₃. Excretion of dimethylselenide with the respiratory air was inhibited by administration of Na₂SeO₃ simultaneously with NaAsO₂. (2) Giving Na₂SeO₃ plus NaAsO₂ had no appreciable effect on the excretion of the trimethylselenonium ion (Me₃Se⁺) into the urine and the feces. (3) Giving Na₂SeO₃ plus NaAsO₂ increaed the excretion into the feces of an insoluble unknown-structure selenium compound, the proportion of which was 10.9% by weight of the given dose of selenium. (4) Giving NaAsO₂ plus Na₂SeO₃ decreased the excretion of dimethylarsinic acid (Me₂AsOOH) and inorganic arsenic into the urine during 120 h after the administration of the reagents, the decreased amount being 5.3% (dimethylarsinic acid) and 7.7% (inorganic arsenic) of the given dose of arsenic, respectively. (5) Giving NaAsO₂ plus Na₂SeO₃ increased the excretion into feces of insoluble unknown-structure arsenic compound and inorganic arsenic, the increased amounts being 10.6% and 7.0% of the given dose of arsenic, respectively. (6) Giving NaAsO₂ plus Na₂SeO₃ decreased the excretion into feces of extractable unknown-structure arsenic compound, and the decreased amount was 4.9% of the given dose of arsenic. (7) It made little difference to the excretion of monomethylarsonic acid [MeAsO(OH)₂] into urine and feces and of dimethylarsinic acid (Me₂AsOOH) into feces whether NaAsO₂ was administered alone or with Na₂SeO₃.     

Effects of arsenic on the organic component of the alga Dunaliella salina

The unicellular marine alga, Dunaliella salina 19/30 was grown in seawater containing an inorganic arsenic concentration (Na₂HAsO₄) up to 2000 mg dm^?3. The cells survived even at 5000 mg dm^?3. The arsenic concentration of the cells increased with an increase of the surrounding arsenic concentration. Arsenic in D. salina was also greatly affected by addition of phosphorus. The arsenic-tolerance behavior of D. salina seemed to suggest that the algae have a function to prevent accumulation of inorganic arsenic by increasing the β-carotene, fatty-acid (C_18:1, C_18:3) and water-extractable carbohydrate content in the cells. Arsenic accumulation also rose steadily with an increase in the nitrogen concentration in the medium.     

Zur Kenntnis von Natriumarseniten im Dreistoffsystem Na2O?As2O3?H2O bei 6°C

Concerning Sodium Arsenites in the Three Component System Na₂O? As₂O₃? H₂O at 6°C Four phases Na₂(H₂As₄O₈) 1c , NaAsO₂ · 4 H₂O 2c , Na₂(HAsO₃) · 5 H₂O 3c , and Na₅(HAsO₃)(AsO₃) · 12 H₂O 4c have been identified in the system Na₂O? As₂O₃? H₂O at 6°C and characterized by X-ray structural analysis. Polymetaarsenite anions, adopt in 1c and 2c , respectively, octet or doublet single chains.     

Effect of cadmium on the accumulation of arsenic in a marine green alga,Dunaliellasp.

To investigate the effect of cadmium on the accumulation of arsenic by Dunaliella sp., the arsenic accumulated in the alga was determined as a function of time for coexistence of the algae with arsenic and cadmium, with batch methodology. Growth of Dunaliella sp. was affected by addition of arsenic (Na₂HAsO₄.7H₂O) and cadmium (CdCl.2.5H₂O). Growth inhibition of Dunaliella sp. was accelerated by coexistence of arsenic and cadmium. The content of arsenic in Dunaliella sp. became a maximum at 15 h after exposure. The arsenic content in the cells was influenced by addition of cadmium to the solution; the arsenic content in the alga derived from growth in a 10 mg As dm ^?3 solution decreased from 2.7 mg g^?1 in the absence of cadmium to 0.35 mg g^?1 for the addition of 100 mg Cd dm^?3. Dunaliella sp. accumulated cadmium in large quantities but, in conditions of coexistence with arsenic and cadmium, the cadmium content in cells decreased with an increase in the concentration of arsenic in the growth medium Cadmium accumulation by Dunaliella sp. was observed in dead cells although arsenic accumulation was not observed. About 85% of arsenic in the cells was in the water-soluble fraction. On the other hand, about 42% of cadmium in the cells was in the water-soluble fraction, and about 55% was in a fraction soluble in cold trichloroacetic acid.     

M+M3+2As(HAsO4)6 and α‐ and β‐M+M3+(HAsO4)2 (M+M3+ = RbAl or CsFe): six new compounds crystallizing in three closely related structure types

The crystal structures of hydrothermally synthesized (T = 493 K, 7–9 d) rubidium aluminium bis[hydrogen arsenate(V)], RbAl(HAsO₄)₂, caesium iron bis[hydrogen arsenate(V)], CsFe(HAsO₄)₂, rubidium dialuminium arsenic(V) hexakis[hydrogen arsenate(V)], RbAl₂As(HAsO₄)₆, and caesium diiron arsenic(V) hexakis[hydrogen arsenate(V)], CsFe₂As(HAsO₄)₆, were solved by single‐crystal X‐ray diffraction. The four compounds with the general formula M⁺M³⁺(HAsO₄)₂ adopt the RbFe(HPO₄)₂ structure type (Rc) and a closely related new structure type, which is characterized by a different stacking order of the building units, leading to noncentrosymmetric space‐group symmetry R32. The second new structure type, with the general formula M⁺M³⁺₂As(HAsO₄)₆ (Rc), is also a modification of the RbFe(HPO₄)₂ structure type, in which one third of the M³⁺O₆ octahedra are replaced by AsO₆ octahedra, and two thirds of the voids in the structure, which are usually filled by M⁺ cations, remain empty to achieve charge balance.     

Spectral and structural analysis of sodium hydrophosphates and hydroarsenates

Anhydrous sodium hydrophosphates and arsenates and heptahxdrates were svnthesized and characterized by IR spectroscopy and X-ray diffractometry. Anhydrous sodium hxdrophosphate and hydroarsenate were found to be isostmctural. Unit cell parameters of Na₂HAsO₄ are calculated. Assignment of IR bands is given and comparative analysis of spectral and structural characteristics of the compounds is performed.     

Effect of Sodium Hydroarsenate on the Kinetics of Reduction of Hydrogen Ions at Iron and on the Hydrogen Diffusion through a Steel Membrane from Aqueous and Ethylene Glycol Solutions of Hydrochloric Acid

Effect of arsenic compounds H₃AsO₄, H₂AsO₄ ^–, and HAsO₄ ^2– on the hydrogen overvoltage, the slow stage of discharge of hydronium ions on the Armco iron, and the hydrogen diffusion through a steel membrane from aqueous and ethylene glycol solutions of hydrochloric acid with a constant ionic strength of unity is considered.     

Determination and pharmacokinetic properties of arsenic speciation in Xiao‐Er‐Zhi‐Bao‐Wan by high‐performance liquid chromatography with inductively coupled plasma mass spectrometry

A method of high performance liquid chromatography with a Hamilton PRP‐X100 ion‐exchange column (250 × 4.1 mm id, 10 μm) coupled to inductively coupled plasma mass spectrometry was employed to generate a full concentration–time profile of arsenic speciation after oral administration. The results exhibited good linearity and revealed that, in the pills, the average arsenic concentration was 10105.4 ± 380.7 mg/kg, and in the water extraction solution, the inorganic As(III) and As(V) concentrations were 220.1 ± 12.6 and 45.5 ± 2.3 mg/kg, respectively. No trace of monomethyl arsenic acid was detected in any of the plasma samples. We then successfully applied the established methodology to examine the pharmacokinetics of arsenic speciation. The resulting data revealed that, after oral administration in rats, the plasma concentration of each arsenic species reached C_max shortly after initial dosing, and that the distribution and elimination of As(V) was faster than that of As(III) and dimethyl arsenic acid. Additionally, the t_1/2 values of As(V), As(III), and dimethyl arsenic acid were 3.4 ± 1.6, 14.3 ± 4.0, and 19.9 ± 1.6 h, respectively. This study provides references for the determination of arsenic speciation in mineral‐containing medicines and could serve as a useful tool in measuring the true toxicity in traditional medicines that contain them.     

Darstellung und Eigenschaften von Blei(IV)-arsenat-Gelen und kristallinem Blei(IV)-hydrogenarsenat-monohydrat

Lead(IV) acetate reacts with aqueous arsenic acid to yield lead(IV) arsenates, the state of which depends on the conditions of precipitation. At room temperature amorphous precipitates or gelatinous masses are obtained. Also clear solutions are obtained, which need sometime to become gelatinous. At 90°C colourless crystalline lead(IV) hydrogenarsenate-monohydrate, Pb(HAsO₄)₂ · H₃O, is obtained, isotypic with lead(IV) hyrdrogen-phosphate-monohydrate.     

Pharmacokinetics of aconitine in rat skin after oral and transdermal gel administrations

The purpose of this study was to evaluate percutaneous penetration and arrhythmogenic effects of aconitine after transdermal administration, compared with the oral route. Skin penetration of aconitine was tested by a microdialysis technique in rats and in vivo recovery was determined by retrodialysis. After oral and transdermal administration of aconitine, dialysate was sampled at 20 min intervals until the end of the experiment for the determination of concentration of aconitine in skin. Blood samples were collected and analyzed using a validated HPLC‐MS/MS method. In addition, we concurrently recorded the electrocardiogram (ECG). The in vivo recovery of aconitine in the skin was calculated to be 39.59%. The C_max values for aconitine absorbed into the skin after oral and transdermal administration were 1.51 ± 0.53 and 2723.8 ± 848.8 ng/mL, respectively, and within the plasma, 215.86 ± 79.29 and 20.92 ± 3.15 ng/mL. The C_max value for the plasma concentration of aconitine after oral administration was approximately 10 times higher than with the transdermal route. For oral administration, the ECG revealed various types of arrhythmias at a period of T_max, which is normal in transdermal gel administration. These results indicate that transdermal aconitine gel is a safe formulation that can deliver the drug in sufficient amounts and safe concentrations to produce therapeutic action in rats. Copyright © 2011 John Wiley & Sons, Ltd.     

Potentiometric Titration of Na2HAsO4, NaPO3, Na4P2O7, and their Binary Mixtures in NaNO3 Melt at 350°C Using a Novel Solid State Glass/TiO2 as pH Indicator Electrode

A solid‐state glass/TiO₂ electrode was fabricated using a transparent conductive titanium oxide film on a glass substrate. The coating of the glass substrate was achieved by a novel simple chemical vapor deposition (CVD) procedure. This electrode can be used as an indicator electrode in potentiometric acid‐base titration. This electrode behaves reversibly and responds to the oxide ion concentration in molten NaNO₃ · Na₂HAsO₄, NaPO₃, Na₄P₂O₇, and their binary mixtures were potentiometrically titrated with Na₂O₂ as titrants in molten NaNO₃ at 350°C, using the above mentioned indicator electrode.     

Vibrational spectra of Te(OH)6.2NH4H2AsO4 and Te(OH)6.2(NH4)2HAsO4

IR and Raman spectra of Te(OH)₆.2NH₄H₂AsO₄.(NH₄)₂HAsO₄ (compound I) and Te(OH)₆.2(NH₄)₂HAsO₄ (compound II) are recorded and analysed. The symmetry of different groups and the vibrational interaction between them are discussed. The observed spectra suggest the existence of HAsO²⁻₄ in II and coexistence of HAsO²⁻₄ and H₂AsO⁻₄ in I. The ammonium ion is found to execute hindered rotation in the lattice in both the compounds.     

Two Modifications of (TeO)(HAsO4) and its Dehydration Product (Te3O3)(AsO4)2 – Three more Examples of Tellurium(IV) with a Fivefold Oxygen Coordination

Two modifications of (TeO)(HAsO₄) were obtained by reacting tellurium dioxide with arsenic acid under boiling conditions (modification I, acid concentration 80 wt‐%) or under hydrothermal conditions (modification II, acid concentration 50 wt‐%). The crystal structures of the two modifications were determined from single‐crystal X‐ray data [modification I: P2₁/c, Z = 4, a = 7.4076(10), b = 5.9596(7), c = 9.5523(11) Å, β = 102.589(8)°, 2893 structure factors, 68 parameters, R[F² > 2σ(F²)] = 0.0247, wR₂(F² all) = 0.0530; modification II: P2₁/c, Z = 4, a = 6.2962(4), b = 4.7041(3), c = 13.9446(8) Å, β = 94.528(3)°, 2549 structure factors, 69 parameters, R[F² > 2σ(F²)] = 0.0207, wR₂(F² all) = 0.0462)]. Dehydration of (TeO)(HAsO₄)‐II at temperatures above 260 °C results in the formation of polycrystalline (Te₃O₃)(AsO₄)₂. Single crystals of the anhydrous product were grown either by heating stoichiometric amounts of the binary oxides TeO₂ and As₂O₅ in closed silica glass ampoules or with higher concentrated arsenic acid (80 wt‐%) under hydrothermal conditions at 220 °C. The common features in the crystal structures of (Te₃O₃)(AsO₄)₂ [P$\bar{1}$ , Z = 4, a = 6.5548(4), b = 7.6281(6), c = 15.0464(15) Å, α = 140.212(6), β = 102.418(9)°, γ = 77.346(5)°, 5718 structure factors, 146 parameters, R[F² > 2σ(F²)] = 0.0351, wR₂(F² all) = 0. 1093] and in that of the two modifications of acidic (TeO)(HAsO₄) are [TeO₅] square‐pyramids and [AsO₄] tetrahedra. In anhydrous (Te₃O₃)(AsO₄)₂ and in (TeO)(HAsO₄)‐II, a layered arrangement of the building units is found, whereas in the (TeO)(HAsO₄)‐I structure strands are formed. Different hydrogen bonding interactions are present in the two modifications of (TeO)(HAsO₄).     

Distribution of 1,4-dioxane by combined inhalation plus oral exposure routes in rats

1,4-Dioxane is used in large amounts by industry. Human exposure to 1,4-dioxane is via both air and water. Recently we reported that the toxicity of chloroform is enhanced when exposure is by multiple exposure routes rather than a single exposure route. In this study, rats were exposed simultaneously to 1,4-dioxane by two routes, inhalation and oral, and the distribution of 1,4-dioxane in the blood, lung, liver, brain, kidney and abdominal fat of rats were determined. To assess the contribution of each route, unmodified 1,4-dioxane (DX) was administered by inhalation and deuterated 1,4-dioxane (DX-d₈) was administered orally, and DX and DX-d₈ were analyzed by mass spectrometer (MS). Exposure by both inhalation and oral administration resulted in DX and DX-d₈ concentrations in the blood and tissues which were higher than when exposure was by either inhalation or oral administration alone. The distribution of 1,4-dioxane in the combined inhalation plus oral administration conformed with its physicochemical properties and the tissue partition coefficients. Our results support the well accepted tenet that when investigating the toxicity of a chemical, the route of exposure is an important consideration, and in addition, our results suggest that when exposure is by multiple routes, exposure by one route may, to some extent, have an affect on exposure by the second route.     

A Water‐Stable Ionic MOF for the Selective Capture of Toxic Oxoanions of SeVI and AsV and Crystallographic Insight into the Ion‐Exchange Mechanism

Selectively capturing toxic oxoanions of selenium and arsenic is highly desired for the remediation of hazardous waste. Ionic metal–organic frameworks (iMOFs) especially cationic MOFs (iMOF‐C) as ion‐exchange materials, featuring aqueous phase stability, present a robust pathway for sequestration of the oxoanions owing to their ability to prevent leaching because of their ionic nature. On account of scarcity of water‐stable cationic MOFs, the capture of oxoanions of selenium and arsenic has been a major challenge and has not been investigated using iMOFs. Herein, we demonstrate large scale synthesis of cationic MOF, viz. iMOF‐1C that exhibits selective capture of oxoanions of Se^VI (SeO₄^2?) and As^V (HAsO₄^2?) in water with a maximum sorption capacity of 100 and 85 mg g^?1, respectively. This represents among the highest uptake capacities observed for selenate oxoanion in MOFs. Further, the ion‐exchange mechanism was directly unveiled by single crystal analysis, which revealed variable modes of host–guest binding.     

A Water-Stable Ionic MOF for the Selective Capture of Toxic Oxoanions of SeVI and AsV and Crystallographic Insight into the Ion-Exchange Mechanism

Selectively capturing toxic oxoanions of selenium and arsenic is highly desired for the remediation of hazardous waste. Ionic metal–organic frameworks (iMOFs) especially cationic MOFs (iMOF-C) as ion-exchange materials, featuring aqueous phase stability, present a robust pathway for sequestration of the oxoanions owing to their ability to prevent leaching because of their ionic nature. On account of scarcity of water-stable cationic MOFs, the capture of oxoanions of selenium and arsenic has been a major challenge and has not been investigated using iMOFs. Herein, we demonstrate large scale synthesis of cationic MOF, viz. iMOF-1C that exhibits selective capture of oxoanions of Se^VI (SeO₄²⁻) and As^V (HAsO₄²⁻) in water with a maximum sorption capacity of 100 and 85 mg g⁻¹, respectively. This represents among the highest uptake capacities observed for selenate oxoanion in MOFs. Further, the ion-exchange mechanism was directly unveiled by single crystal analysis, which revealed variable modes of host–guest binding.