Measurement of arsenic in sectioned hair samples by instrumental neutron activation analysis

In a recent Texas murder case, bundles of head hair from the female victim (aligned with all root ends together) were washed, cut into 7 mm sections, air-dried and weighed, activated in a nuclear reactor neutron flux, and then counted with a Ge(Li) detector/4096-channel gamma-ray spectrometer. In each of the 15 samples, the 559 keV gamma-ray peak of 26.3 hour⁷⁶As was measured. In the section closest to the scalp, an arsenic concentration of 107 ppm was found (cf. a normal level of about 1 ppm As). Barium ingestion was also possible so Ba was looked for, but not found. The victim's husband was found guilty of murder by chronic arsenic poisoning.     

Characterization of the neutron flux gradients in typical irradiation channels of a TRIGA Mark II reactor

The neutron distribution in a defined volume (gradient) for different matrices (air, water, cellulose, biological material and silicon dioxide) in two typical irradiation channels (pneumatic tube (PT) and IC40-channel in the carousel facility) in the TRIGA Mark II reactor at the Joef Stefan Institute (IJS) was studied. Our experiment was based on inserting Fe wires (flux monitors) into the chosen matrices. The wires were cut into small pieces after irradiation and the induced activities of ⁵⁹Fe measured. The results showed that for the studied geometry the average spatial thermal neutron flux inhomogeneities (for five studied matrices) are about 2.3% in the PT-channel and about 2.9% in the IC40-channel.     

Determination of total arsenic in serum and packed cellsof patients with renal insufficiency

In order to investigate the arsenic level in serum and packed cells of patients with renal insufficiency, total arsenic (As) concentrations were determined with hydride generation atomic absorption spectrometry (HGAAS) in serum (S) and packed cells (PC) of 31 non-dialyzed patients. The accuracy of the method was tested by the analysis of arsenic in 3 certified reference materials. Patients showed a three-fold increase of arsenic concentrations in serum and a two-fold increase of arsenic in packed cells compared with controls. Patients (n=10) with higher serum creatinine (>2.0 mg/dL), urea (>0.70 g/L) and urinary protein (mean ±SD: 1.12±0.82 g/L) showed higher arsenic concentrations (5.8±3.3 g/L in serum and 18.0±16.7 g/kg in packed cells) compared with those with lower creatinine (<1.6 mg/dL), urea (<0.6 g/L) and urinary protein (mean ±SD: 0.27±0.82 g/L) (n=16, serum arsenic 1.2±1.2 g/L, packed cells arsenic 2.6±1.9 g/kg). The significant differences (both p<0.001) in S and PC-arsenic levels of patients in group I and II implies a relationship between the arsenic level and the degree of chronic renal insufficiency.Dedicated to Professor Dr. Peter Brätter on the occasion of his 60th birthday     

Effective arsenic removal using polyacrylonitrile-based ultrafiltration (UF) membrane

Applicability of polyacrylonitrile (PAN)-based negatively charged ultrafiltration (UF) membrane for effective arsenic removal has been demonstrated, to our knowledge, for the first time. The hydrolysis of PAN-based UF membrane surface by NaOH leading to the formation of carboxylate (COO⁻) groups and reduction in initial pore size rendered As-V rejection capability by Donnan exclusion principle. A lowering in pore size was indicated by the reduction in water flux and elevation in rejection of protein and polyethylene glycol (PEG). NaOH treatment leading to formation of carboxylate group on the membrane surface was indicated by FTIR-ATR, while contact angle measurement indicated increased hydrophilicity. This treatment rendered membrane surface smoothening as confirmed by SEM and AFM analyses. The molecular weight cut off after the NaOH treatment was found to be 6 kDa. The rejection of pentavalent arsenic (As-V) by these surface modified membranes was studied with different feed concentration, cross-flow velocity, pressure, temperature and pH. Experiments with 50 ppb As-V in feed showed that arsenic rejection was close to 100% and remained constant up to 6 h. Feed sample concentration of 1000 ppb and 50 ppm of As-V showed >95% rejection at pH 7 and room temperature, but for 1000 ppm feed concentration, the rejection was 40–65%. For concentrations ≤50 ppm of arsenic in the feed, the rejection coefficient was not dependent on cross-flow velocity or transmembrane pressure. The rejection for 1000 ppm concentration of As-V varied from 40 to 65% with variation in the cross-flow velocity and transmembrane pressure as the concentration polarization was important.     

Untersuchungen an metallischen Werkstoffen und Schlacken aus dem Bereich von Ugarit (Ras Shamra,Syrien)

Zusammenfassung Untersuchungen an metallischen Werkstoffen und Schlacken aus der Bronzezeit von Ugarit (Ras Shamra) haben gezeigt, daß die dort gefundenen Kupferwerkstoffe aus zumindest teilweise sulfidischen Erzen hergestellt wurden. Die untersuchten Schlackenstücke weisen unterschiedliche Silikate auf, die jedoch durch ungleichmäßige Temperaturen in den Verhüttungsöfen entstanden sein können. Vielleicht handelt es sich um Votivgaben, da kein Verhüttungsofen in der Nähe gefunden wurde und Kupfer-Erze erst mehrere hundert Kilometer entfernt bei Ergani-Maden bzw. in Zypern vorhanden sind. Neben reinen Arsenbronzen werden auch zinnhaltige Arsenbronzen gefunden. Maßgebend in der damaligen Zeit dürfte die Härte, die durch Kalthämmern erzielt wurde und die Farbe der Werkstoffe gewesen sein. Bei einer reinen Arsenbronze, einem Beilbruchstück (121± ₁₆ ¹⁰ HV1) vermutlich aus Zypern wurde eine Festigkeit R_m von 254 N/mm², bei einer Bruchdehnung von 5% und bei einem Beilbruchstück aus Ugarit mit geringem Gehalt an Arsen und hohem Gehalt an Zinn eine Festigkeit von R_m=360 N/mm² bei einer Bruchdehnung von 24% bei einer Härte von 130±3HV1 gemessen. Die Herstellung von messingähnlichen Legierungen mit Gehalten von 12% Zink, wahrscheinlich aus bleihaltigem Galmei wurde an einem Fingerring, der 1400 v. Chr. datiert wurde, ferner an einem Fabeltier mit einem Ankhzeichen auf einer Sonnenscheibe zwischen Hörnern bestätigt. Einlagen bestehen aus goldarmem Elektron.

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Investigations of metallic materials and copper slag from the area of Ugarit (Ras Shamra, syria)

Summary Investigations on bronze age metallic materials and on slags from Ugarit (Ras Shamra) have shown, that the copper investigated was produced from at least in part sulfidic ores. The slag pieces contain different silicates, which may have been produced at different temperatures within the smelting furnaces. Perhaps the slag pieces were votive gifts, as there were no smelting furnaces in the surroundings. Copper ores are to be found only in several hundred kilometers distance near Ergani-Maden and in Cyprus. Besides pure arsenic bronzes there are also bronzes which contain besides arsenic a high addition of tin. During Bronze Age the hardness which was increased by cold deformation to more than 200HV1 and the corresponding strength and also the colour of the metallic materials may have been the fundamental aspect for the smith. The tensile strength of an arsenic bronze axe, probably from Cyprus was 276 N/mm², elongation 5% and hardness 121± ₁₆ ¹⁰ HV1; the tensile strength of a bronze axe from Ugarit containing less arsenic and much more tin was 360 N/mm², elongation 24% and hardness 130±3HV1. The production of brass type alloys containing 12% Zn, probably from Galmei containing lead was prooved in a fingerring dated 1400 B. C. and on a fable-animal with the sign of Ankh on a sundisk between the horns. Round light spots on the body were found to have been fabricated from electron with a low content of gold.

     

Determination of arsenic in glass and raw materials for glass via quartz-tube hydride generation AAS after separation by solvent extraction

Summary A method is described for the determination of traces of arsenic in glass and raw materials for glass. After a digestion with hydrofluoric acid/sulphuric acid for glass and silica containing materials and varied digestion variants the arsenic is separated from the sample matrix by solvent-extraction of arsenic(III) chloride with toluene and back-extraction into water. The following determination is made by hydride generation atomic absorption spectrometry after atomisation in a heated quartz tube. A volatilization of arsenic during the digestion, different reagents for the oxidation and reduction of arsenic as well as the selectivity of the solvent extraction with regard to different interfering elements were investigated. It has been found that with the method developed, also at high concentrations of interfering elements, arsenic can be separated and a nearly interference-free determination of arsenic in glass and in raw materials for glass is possible. For example, at antimony concentrations of 60% (m/m) in the sample the detection limit is 0.5 g/g As₂O₃. The over-all detection limit is 0.05 g/g As₂O₃. The relative standard deviation is 5.7% (n=4) at a concentration of 3.6 g/g As₂O₃.     

Neutron activation analysis of arsenic species

Inorganic arsenic, MMA, DMA and arsenobetaine (As) were separated by the use of cation and anion exchange chromatography combined with neutron activation. Two complementary approaches were used: firstly, authentic, non-irradiated arsenic compounds, either singly or in mixtures, were separated and NAA of the fractions used as an element specific detection method. Secondly, the arsenic compounds were neutron irradiated under different conditions and for different times and the products separated and quantified. The⁷⁶As labeled species (mono-, di and trimethylated) were then additionally used to calibrate and improve the column separations. Using the separations developed, arsenic species in samples of shrimps and the standard reference material DORM-1 were determined, after an extraction step, using ion exchange chromatography followed by INAA of the fractions collected.     

Determination of arsenic in the presence of high copper concentrations using flow-injection analysis-hydride atomic absorption spectrometry

Summary Arsenic is determined in environmental samples containing metal ions up to 10,000 mg/l copper, 200 mg/l lead, 200 mg/l iron and 200 mg/l nickel by using the FIA-hydride-AAS technique. In the presented sample preparation method arsenic is prereduced and the interfering metal ions are precipitated. As signal depressions from metal ions are excluded, a detection limit of 1 g/l arsenic is achieved.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday     

Evaluation of high-pressure microwave digestion methods for hydride generation atomic absorption spectrometric determination of total selenium and arsenic in sediment

Five closed-vessel microwave digestion methods were compared for the accurate determination of arsenic and selenium in NIST SRM 1645 River Sediment by flow-injection hydride-generation atomic absorption spectrometric methods. The digestion methods using five different acid mixtures (HNO₃/ H₂SO₄, HNO₃/HCl0₄, HNO₃/HCl, HNO₃/HCl/HF, HNO₃/H₂SO₄/HClO₄) were all found to be reliable for the determination of the analytes. Taking into consideration the safety and suitability for the analysis of other metals, the methods based on the use ofaqua regia are recommended for closed vessel microwave digestion with pressure control. Using the quick digestion program, the presence of up to 10% organic content in soil samples did not adversely affect the closed vessel digestion and did not cause the loss of volatile analytes. After digestion, opening the vessel under an inner pressure of below 345 kPa (50 psi) had no effect on the accuracy of the results. The recommended digestion methods (HNO₃/HCl and HNO₃/ HCl/HF) for the reliable determination of arsenic and selenium in different sediment samples were demonstrated. The calculated detection limits (3 _b ) were less than 0.030 g/g and 0.033 g/g for arsenic and selenium, respectively. All analytical results for arsenic and selenium in SRM 1645 River sediment, NRCC BCSS-1 Marine Sediment and NIES CRM Pond Sediment were within or near the certified and reported ranges, with the exception of selenium in NIES CRM No. 2 Pond Sediment.