Determination of nitrogen in uranium and uranium-oxide by high-temperature gas-extraction

Summary The reducing fusion gas extraction method has been used for the determination of nitrogen in uranium metal and uranium dioxide reference materials at levels of about 10–15g·g^–1. It has been found that when extracting at temperatures above 2700° C the use of a platinum flux is no longer necessary. Pure nitrogen and nitrogen-helium mixtures were used for calibrating the detection unit in the range of 1.5–670 g. The calibration of the extraction was performed with metallic reference materials in the range of 8–331 g N₂ content.

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Bestimmung von Stickstoff in Uran und Uranoxid durch Hochtemperatur-Gasextraktion

Zusammenfassung Die Gasextraktion aus reduzierender Schmelze wurde zur Stickstoffbestimmung in Uranmetall- und Urandioxid-Referenzmaterialien bei Gehalten von 10–15 g·g^–1 angewendet. Bei Temperaturen über 2700° C ist kein Platinbad mehr erforderlich. Zur Eichung der Detektionseinheit im Bereich von 1,5–670 g wurden reiner Stickstoff oder Stickstoff-Helium-Mischungen benutzt. Zur Eichung der Extraktion wurden metallische Referenzmaterialien mit (8–331g) N₂ eingesetzt.

     

Bestimmung von Chrom in menschlichem Serum und Plasma mit der flammenlosen Atomabsorptions-Spektrophotometrie

Zusammenfassung Die bis heute in der Literatur mitgeteilten Werte für Chrom im Serum nüchterner gesunder Probanden unterscheiden sich um Größenordnungen. Die in der vorliegenden Arbeit mitgeteilten Untersuchungen betreffen die analytische Problematik der Chrombestimmung mit Hilfe der flammenlosen Atomabsorptions-Spektrometrie, wobei aufgezeigt wird, daß diese Methodik für die Chrombestimmung in biologischem Material ohne großen statistischen Aufwand zu keiner sicheren Beurteilbarkeit und Interpretierbarkeit der gemessenen Werte führt. Mit Hilfe synthetischer Chromkomplexverbindungen werden die Probleme der Standardaddition zur Chrombestimmung untersucht. Unter Berücksichtigung der Blindwerte und der daraus resultierenden Nachweisgrenze sowie Garantiegrenze für Reinheit, wurde Chrom in einem Standardreferenzmaterial (1569 Brewers yeast [U. S. National Bureau of Standards]) im Rahmen eines Ringversuchs zur Chromanalyse sowie im Serum und Plasma von 41 Probanden bestimmt. Für das Referenzmaterial wurde ein Wert von 45±4 mol/kg (2,3±0,2 g/g) ermittelt. Der Referenzwert betrug 41±1 mol/kg (2,12±0,05 g/g). Im Serum wird eine lognormale Verteilung der Chromkonzentration mit den zentralen Parametern ±_M=132,2 nmol/l (0,72,2 g/l) ermittelt. Im Plasma lagen die Werte zwischen 20 und 30 nmol/l (1–1,5 g/l). Aufschluß, Durchführung der Bestimmung sowie die biologische Bedeutung und Interpretation des Parameters Chrom im Serum und Plasma werden eingehend diskutiert.

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Determination of chromium in human serum and plasma by flame-less atomic-absorption spectrophotometry

Summary Concentrations of Cr in serum of overnight fasting volunteers differ over a wide range in the literature. The investigations of the analytical problems of Cr determination by flameless atomic absorption spectrometry underline the necessity of statistical methods for the interpretation of the measurements of Cr in biological matrices. With nine different synthetic chromium complexes the method of standard addition was investigated. Considering the blank values, the limit of detection and the limit of guarantee for purity, Cr was determined in the standard reference material 1569 brewers yeast (National Bureau of Standards) with 45±4 Mol · kg^–1 (2.3±0.2g·g^–1), compared with the reference data 41±1 Mol·kg^–1 (2.12±0.05 g±g^–1). In serumuuuuu we found a lognormal distribution with the central parameters 132.2 nMol ·1^–1 (0.72.2 g·1^–1). In plasma the values were in the range between 20 and 30 nMol·1^–1 (1–1.5 g·1^–1). The ashing process and the determination are demonstrated and discussed in detail.

     

Spectrophotometric determination of microamounts of thorium with disodium salt of 2-(2-hydroxy-3,6-disulfo-1-naphthylazo)-benzenearsonic acid (Thorin) as a chromogenic reagent

A sensitive spectrophotometric method has been developed for the determination of microamounts of thorium using 0.05% thorin in a 3M perchloric acid solution as a chromogenic reagent and measuring the absorbance at 544 nm. The complex of thorium thus formed, is stable for more than two months with a constant absorbance of ±0.55%. Beer's law is obeyed from 0 to 25 g g^–1 of thorium in a solution with a molar absorptivity (544 nm) = 1.69×10⁴ M^–1 cm^–1 at 26±1 °C. Among the anions tested, only phosphate, acetate and cyanide at >200-fold excess of thorium interfere in the determination, whereas cations like Zn(II), Al(III), Na(I), Mg(II), and Ca(II) do not effect the absorbance. Thorium can be determined in the presence of oxalate, nitrate, tartrate, sulfate, thiosulfate, citrate, and ascorbate. The accuracy of the method has been checked by measuring the known concentration of thorium in the range of 100 g-5 mg g^–1 and found to be in the range of 7.7–0.9%. The method has been applied successfully to determine thorium at g g^–1 level in local ore samples with a precision of ±0.3%. The sensitivity of the method on Sandell's scale is 0.082±0.002 g g^–1 cm^–1.     

Inductively coupled plasma atomic emission spectrometric determination of arsenic in mussel products

Summary A precise, accurate procedure is proposed for the determination of arsenic in mussel products by inductively coupled plasma atomic emission spectrometry. Organic matter is destroyed by dry ashing. Experimental conditions for the determination of arsenic were selected and an interference study was carried out. The methodology developed has a detection limit of 0.1 g g^–1, a relative standard deviation of 3%, and a recovery percentage of 98±2%. The accuracy of the method was checked by analysis of a certified sample of NIST oyster tissue (certified 14.0±1.2 g g^–1; found 14.1±1.1 g g^–1). The proposed procedure was used to analyze real samples of mussel products.     

ET-AAS in the Analysis of high-purity mercury

ET-AAS is investigated for the analysis of high purity mercury. Two possibilities are proposed: ET-AAS determination of trace analytes in the presence of high mercury concentrations or after matrix separation by reduction. The ET-AAS analysis of high-purity mercury under optimal instrumental parameters permits fast and reproducible determination of 0.03 gg^–1 Al, Cd and Mn; 0.05 gg^–1 Cu, Co, Cr, Fe, Ni and Pb and 0.2 gg^–1 V. Preliminary mercury matrix reductive separation with ascorbic acid allows determination of 0.005 gg^–1 Cd, 0.02 gg^–1 Cu, Cr and Mn, 0.03 g g^–1 Co, Ni and Pb, 0.05 g g^–1 Al and Fe and 0.1 gg^–1 V, but the reproducibility is lower. The main advantage of the second procedure is that it avoids laboratory and instrument pollution with toxic mercury.     

Determination of oxygen by deuteron-induced PIPPS

Using the 871-keV¹⁶O p/1,0/ prompt -ray, oxygen was determined with a relative precision of ±3.8% at a concentration level of 120 g g^–1. The sensitivity of the method is below 10 g g^–1. 50 nm oxide layers on silicon wafers can be determined with a relative precision of 10%. A chamber for transporting targets sensitive to atmospheric gases and humidity is described.     

Determination of magnesium in botanical reference materials by instrumental neutron activation analysis

Instrumental neutron activation analysis (INAA) was applied to the rapid determination of magnesium in the botanical reference materials Beech Leaves-100 and Spruce Needles-101. The magnesium content was quantitatively determined by measuring the gamma-ray photopeak at 1014 keV of the short-lived radionuclide²⁷Mg (9.46 m). The magnesium concentrations in the two materials were found to be 834.6±50.2 g·g^–1 dry weight and 618.6±36.2 g·g^–1, respectively. When assaying a 0.1 g sample under the same experimental conditions the limit of detection is 30 g of Mg.Work carried out at Risø National Laboratory, Isotopes Division, DK-4000 Roskilde, Denmark.     

A toxic reagent-free method for normal-phase matrix solid-phase dispersion extraction and reversed-phase liquid chromatographic determination of aldrin,dieldrin, and DDTs in animal fats

A method for the determination of aldrin, dieldrin, DDT, DDE, and DDD contamination in animal fats (beef tallow, lard, and chicken fat) without using toxic reagents is developed, that uses high-performance liquid chromatography after the sample has been prepared by matrix solid-phase dispersion (MSPD) with acidic alumina oxide. A reversed-phase C₁-silica column with a mobile phase of 50% (v/v) ethanol solution (in water) and a photo-diode array detector were used for the determination. Average recoveries of the target compounds (0.2–5.0 g g^–1) ranged from 84–98%, with coefficients of variation of <5%. The limits of quantitation were 0.16 g g^–1 for AD, 0.10 g g^–1 for DD, 0.06 g g^–1 for DDT, 0.07 g g^–1 for DDE, and 0.05 g g^–1 for DDD. No toxic reagents were used at all.     

Assessment of the essential element and heavy metal content of edible fish muscle

The aim of this work was to determine the concentrations of some essential and toxic elements in the muscle of ten species of commercial fish consumed in Portugal. We combined two different techniques for determination of the elements—energy-dispersive X-ray fluorescence (EDXRF) was used to quantify K, Ca, Fe, Zn, Se, Rb, and Sr and flame atomic-absorption spectrometry for analysis of Cr, Ni, Cu, Cd, Hg, and Pb. The latter technique was used because of its higher sensitivity, because these elements were not detected by EDXRF. The results obtained show a similar pattern for the trace elements. K and Ca are present at the highest concentrations in all the samples studied, from 0.6–1.3% and from 0.04–0.08%, respectively, followed by Zn, Fe, Sr, Se, and Rb. Sr is present at higher concentrations than Rb in all the species studied except meagre. Concentrations of the elements in octopus do not follow this pattern—Fe is present at a higher concentration than Zn. Low concentrations of Cr (0.66–1.5 g g^–1), Ni (0.11–0.24 g g^–1), Cd (0.01–0.08 g g^–1), Hg (0.49–2.74 g g^–1), and Pb (0.02–0.06 g g^–1) were observed in all the samples analysed. The concentration of Hg was highest in Helicolenus dactylopterus—5.4 g g^–1 in one sample.     

The determination of boron in biological materials by neutron irradiation and prompt gamma-ray spectrometry

A prompt-gamma neutron activation technique has been developed using the (n, ) apparatus situated at the O degree through-tube of the Imperial College CONSORT II Reactor with a thermal neutron flux at the target position of approximately 2×10⁶ n cm^–2 sec^–1, and a Compton-suppression system involving a lithium-drifted germanium (Ge(Li)) detector and a sodium iodide anti-Compton shield. Boron levels of 1–5 g g^–1 (detection limit 0.05 g B for 10,000 sec period of measurement) can be attained using the Compton-suppression system with graphical inter-polation correction for the 472 keV sodium-ray peak contribution to the Doppler-broadened 478 keV boron gamma-ray peak resulting from the¹⁰B(n, )⁷Li reaction. Very good agreement is reached for boron levels compared using this system for various Standard Reference Materials and other published values. Measurement of the boron content of bone and tooth samples from rheumatoid arthritis individuals shows lower levels, (p<0.05); 16.13±7.53 g g^–1, when compared with a control population; 19.79±4.18 g g^–1. A positive correlation existed between the boron content of bone and tooth material for each study group. Results indicate that boron availability may be associated with rheumatoid arthritis.     

Heavy metals in selected soils of the semi-arid region of Nigeria

Eight soil profiles developed on crystalline basement complex rocks in the semi-arid region of Nigeria were analyzed for total contents of cesium (Cs), chromium (Cr), cobalt (Co), hafnium (Hf), iron (Fe), lanthanum (La), lutetium (Lu), scandium (Sc), thorium (Th), uranium (U) and ytterbium (Yb). The contents range from 50.3–95.4 Cs, 16.1–58.1 Cr, 0.6–9.0 Co, 9.0–34.8 g g^–1 Hf, 0.31–3.69% Fe, 17.2–60.7 La, 60.4–90.6 Lu, 2.6–12.6 Sc, 8.3–21.5 Th, 4.7–9.2 U and 3.6–92 g g^–1, Yb. Their corresponding means were 68.4, 35.1, 4.0, 19.9 g g^–1, 1.70%, 37.1, 79.4, 6.5, 14.7, 6.7 and 5.0 g g^–1. In general, total Cs, Co, Fe, La, U and Yb increased with further increase with depth. On the other hand, Lu, Sc and Th showed no distinct vertical distribution within the profiles. All eleven elements were correlated with the amounts of clay present in the soils, the correlation being stronger for Cs, Th, Yb, Cr and Lu.     

Determination of traces of sodium alkylbenzenesulphonate by high-performance liquid chromatography. Application to water

Summary For the trace determination of sodium alkylbenzenesulphonate (ABS) by HPLC the following conditions were employed: Shimadzu ZORBAX SIL Column (5 m, 4.6 mm i.d. x 150 mm) as stationary phase, 0.2% ammoniaethanol (v/v) as mobile phase, UV detector at 225 nm, injection volume 12 l. The chromatograms of ABS were simple and sharp (detection limit of ABS 0.02 g in 12 l of ethanol). The calibration curves of ABS were linear in a concentration range of 0.03 0.3 g in 12 l of ethanol. In the case of linear sodium dodecylbenzenesulphonate positive errors of 1 4% were caused by non-ionic surfactants or laurylsulphate (6 times excess), 10 50% positive errors were caused by 2 6 times excess of household detergents.Standard water samples containing ABS were treated with a weak base anion-exchange resin, the adsorbed ABS were eluted, and then determined either by HPLC or by the methylene blue spectrophotometric method. Recoveries of ABS in water were about 92 107% by HPLC.

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Bestimmung von Spuren Natriumalkylbenzolsulfonat mit Hilfe der HPLC. Anwendung auf Wasser

Zusammenfassung Für die Spurenbestimmung von Natriumalkylbenzolsulfonat (ABS) durch HPLC werden die folgenden Bedingungen empfohlen:Shimadzu ZORBAX SIL (5 m, 4,6 mm x 150 mm) als stationäre Phase, 0,2% Ammoniak/Ethanol als mobile Phase, UV-Detektor bei 225 nm, Injektionsvolumen 12 l. Die erhaltenen Chromatogramme sind einfach und scharf (Nachweisgrenze 0,02 g in 12 ml Ethanol). Die Eichkurven sind im Konzentrationsbereich von 0,03–0,3 g in 12 l Ethanol linear. Im Falle des linearen Natriumdodecylbenzolsulfonats werden bei Anwesenheit von nicht-ionischen oberflächenaktiven Substanzen oder von Laurylsulfat in 6fachem Überschuß positiver Fehler von 1–4% erhalten; bei 2–6fachem Überschuß von Haushaltswaschmitteln ergeben sich positive Fehler von 10–50%.Standard-Wasserproben werden zunächst einer Behandlung mit einem Anionenaustauscher unterzogen, die adsorbierten ABS eluiert und durch HPLC oder nach der Methylenblaumethode analysiert. Wiederfindungsraten liegen bei 92–107%.

     

Trace element analysis of some shaving powders commonly marketed in Nigeria using instrumental neutron activation analysis

Instrumental neutron activation analysis (INAA) technique has been employed viak ₀ approximation method to determine elemental composition of five shaving powders commonly marketed in Nigeria. Fe displayed the highest concentrations in the range 1000–2000 g·g^–1. Na and Zn concentrations were established in the range 200–400 g·g^–1. Heavy elements like Ga, La, Cr, Co, Ag, Ce and Nd concentrations were noted in the lower range of 1–10 g·g^–1 Br, As, Sb, Sm, Eu, W, Cs, Tb, Yb, Hf, Ta, Th and U concentrations were established in even lower traces in the <1 g·g^–1 range. Results obtained for a certified reference material, CANMET BL-1 and CERT (in house) Kaolin standard compared favourably with the literature values thus establishing the results presented for the shaving powders.     

Platinum concentration in silicone breast implant material and capsular tissue by ICP-MS

Inductively coupled plasma-mass spectrometry (ICP-MS) was used to determine the concentration of platinum (Pt) in silicone breast implant gel (range, 0.26–48.90 g g^–1 Pt; n=15), elastomer (range, 3.05–28.78 g g^–1 Pt; n=7), double lumen (range, 5.79–125.27 g g^–1 Pt; n=7), foam (range, 5.79–8.36 g g^–1 Pt; n=2), and capsular tissue (range, 0.003–0.272 g g^–1 Pt; n=15). The results show that very high levels of Pt are present in the encasing elastomer, double lumen, and foam envelope materials. Silicone breast implants can be a source of significant Pt exposure for individuals with these implants.     

Direct determination of arsenic in sea water by electrothermal atomization atomic absorption spectrometry using D2 and Zeeman background correction

Arsenic in sea water was determined directly by graphite furnace atomic absorption spectrometry (GFAAS) using palladium nitrate as chemical modifier, at an optimum concentration of 15 mg l^–1. Deuterium and Zeeman effect background correction were compared and gave detection limits of 0.6 and 0.8 g l^–1, respectively. Precisions between 8 and 2%, for both correctors, were obtained with an injection volume of 40 l. The accuracy obtained with different reference materials: CRM-403 (1.461 g kg^–1), NASS-4 (1.26 ±0.09 gl^–1) and IAEA/W-4 (24–31 g l^–1) was studied for large injection volumes for both background correction systems. Interferences by chloride, sodium, potassium, calcium and silicon were removed by Zeeman correction, whereas deuterium correction was much less effective and was insufficiently accurate for sea water samples.     

Extractive spectrophotometric determination of dioxouranium(VI) with the sodium salt of hexamethyleneiminecarbodithioate

The optimum conditions for the extractive spectrophotometric determination of dioxouranium(VI) with hexamethyleneiminecarbodithioate(HMICdt) have been established. Dioxouranium(VI) reacts with this ligand at pH 4.5 to form a yellowish-orange uncharged 12 metal-ligand complex which can be extracted by chloroform. The calibration graph was linear in the range of 1–20 g ml^–1 of dioxouranium(VI) at 335 nm. The molar absorptivity of the extracted species is 5.952×10³ l mol^–1 cm^–1 with Sandell's sensitivity of 0.04 g cm^–2. The average of 10 determinations of dioxouranium was 49.75 g for the samples containing 50 g of U(VI) and the variation from the mean at 95% confidence limit was 49.75±0.5955.     

Continuous ultrasound-assisted extraction of cadmium from legumes and dried fruit samples coupled with on-line preconcentration-flame atomic absorption spectrometry

Cadmium was continuously extracted with diluted nitric acid from legumes and dried fruit samples using a simple, rapid and continuous ultrasound-assisted extraction system. A minicolumn packed with a chelating resin (Chelite P, with aminomethylphosphoric acid groups) was placed between the extraction unit and the detector for cadmium preconcentration. The cadmium content in the acid extract was retained into the minicolumn, and elution was carried out with hydrochloric acid, with this trace metal continuously monitored by flame atomic absorption spectrometry. An experimental design (Plackett-Burman 2⁶×3/16) was used to optimize the continuous leaching procedure and the preconcentration step. The method allowed a total sampling frequency of 10 and 14 samples per hour for legumes and dried fruit, respectively. The procedure displayed good precision (2.0 and 2.5%, respectively, expressed as relative standard deviations) for samples containing 0.202±0.005 g g^–1 Cd (broad bean) and 0.239±0.004 g g^–1 Cd (peanut). Detection limits of 0.014 g g^–1 Cd for 60 mg of legume samples and 0.011 g g^–1 Cd for 80 mg of dried fruit samples were obtained. The method was successfully applied to the determination of trace amounts of cadmium in legumes and dried fruit samples.     

Application of l-cysteine-capped nano-ZnS as a fluorescence probe for the determination of proteins

Nanometer-sized l-cysteine-capped ZnS particles have been synthesized and used as a fluorescence probe to investigate the effect of proteins on fluorescent intensity. With =190 nm, maximum and constant synchronous fluorescence enhancement was produced at 267 nm and pH 5.12 in the presence of proteins. A highly sensitive synchronous fluorescence method for the rapid determination of proteins has been developed. Under optimum conditions, calibration graphs are linear over the range 0.03–8.0 g mL^–1 for bovine serum albumin (BSA), 0.01–6.0 g mL^–1 for human serum albumin (HSA), 0.05–8.0 g mL^–1 for -globulin (-G), and 0.04–4.0 g mL^–1 for ovalbumin, respectively. The relative standard deviations of seven replicate measurements were 1.75% for 1.0 g mL^–1 BSA, 1.90% for 1.0 g mL^–1 HSA, 1.65% for 1.0 g mL^–1 -G, and 2.32% for 1.0 g mL^–1 ovalbumin.     

Die Bestimmung von 800 bis 30μg Blei(II) durch potentiometrische Titration mit Molybdat

Zusammenfassung Die Bestimmung von 800 bis 30g Pb(II) durch potentiometrische Titration mit Molybdat unter Verwendung einer bleispezifischen Elektrode wurde untersucht. Unter geeigneten Bedingungen sind mit 4·10^–3 M Molybdat 800 bis 300g Pb(II) in wäßriger Lösung mit einer Genauigkeit von ±0,57% bzw. 0,45% und einer Reproduzierbarkeit von ±0,43% bzw. ±0,30% (Standardabweichung=0,25% bzw. 0,17%) je nach Titrationsart automatisch bzw. manuell bestimmbar.Zur Bestimmung von Pb(II)-Mengen <300g ist eine 2·10^–3 M Molybdatlösung zu verwenden. 300 bis 100g Pb(II) sind in wäßriger Lösung mit zufriedenstellenden Resultaten bestimmbar, jedoch verbessert eine Titration in 40% igem Ethanol nicht nur die Genauigkeit in diesem Bereich, sondern erlaubt auch noch 30g Pb(II) mit einer Genauigkeit von ±1% und einer Reproduzierbarkeit von ±2% (Standardabweichung aus 20 Titrationen von 100g Pb(II)= 0,60%) zu bestimmen.Die Titration von 300–800g Pb(II) in wäßriger Lösung und von 30–300g Pb(II) in 40% igem Ethanol läßt sich auch in 0,1M NaNO_3– 0,1M NaClO_4– Lösung durchführen und ermöglicht somit auch zuverlässige Bleibestimmungen in organischen Verbindungen nach Mineralisierung mit HNO₃–HClO₄–H₂O₂.

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The determination of 800 to 30 g lead(II) by potentiometric titration with molybdate

Summary The determination of 800 to 30g Pb(II) by potentiometric titration with molybdate by using a lead(II)-selective electrode was investigated. Under suitable conditions, 800 to 300g Pb(II) in aqueous solution by automatic or manual titration with 4·10^–3 M molybdate can be determined with an accuracy of ±0.57% and ±0.45% and a precision of ±0.43% and 0.30% (standard deviation=0.25% and 0.17%, resp.).For determining amounts of Pb(II) below 300g, a 2·10^–3 M molybdate solution has to be used. Although 300 to 100g Pb(II) are determinable again in water with satisfactory results, the titration in 40% ethanol is however more reliable: in this medium, amounts of 300 to 30g Pb(II) can be determined with an accuracy of ±1% and a precision of ±2% (standard deviation from 20 titrations of 100g Pb(II)=0.60%).The titration of 300–800g Pb(II) in water and of 30–300g Pb(II) in 40% ethanol is also possible in 0.1M NaNO_3– and 0.1M NaClO_1– medium and can be used in the lead determination in organic compounds after mineralization with HNO₃-HClO₄-H₂O₂.