Nuclear interferences of uranium and thorium in a reactor neutron activation analysis determination of cerium using the radionuclides141Ce and143Ce

The interference contributions of uranium and thorium to the determination of cerium based on radionuclides¹⁴¹Ce and¹⁴³Ce produced by irradiation in a reactor core was determined. The values of the interference contributions for¹⁴¹Ce were 0.28±0.01 g Ce/g U and /2.01±0.05/x10^–3 g Ce/g Th, and for¹⁴³Ce 1.33±0.03 g Ce/g U and /9.0±0.2/x10^–3 g Ce/g Th.     

Untersuchungen zur Bestimmung von Spurenelementen in Blutserum mit Hilfe der Totalreflexions-R?ntgenfluoreszenzanalyse

Summary The quantitative determination of trace elements in human blood serum by Total Reflection X-Ray Fluorescence Analysis (TXRF) is influenced by absorption- and reflection-effects caused by the organic (proteins) and inorganic (P, S, Na, K, Ca, Cl) matrices. To minimize these effects we have developed a sample preparation technique based on the decomposition of the organic matrix and followed by the separation of the trace elements from the organic matrix by ion-exchange. The described method enables the simultaneous determination of K (1584 g), Ca (666 g), Fe (22 g), Cu (9.6 g), Zn (8.8 g), Se (0.97 g), Sn (1.3 g), Pb (0.12 g) and Rb (1.6 g) (obtained values in parentheses).

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Herrn Prof. Dr. G. Tölg zum 60. Geburtstag gewidmet     

Human prostate specific antigen (hPSA) purification and establishment of hPSA radioimmunoassay

Human prostate specific antigen (hPSA) RIA was developed with hPSA and anti-PSA prepared in our laboratory. Its standard curve was linear with a sensitivity of 0.5 g/L. Serum PSA levels of 130 normal males ranged from 0 to 3.5 g/L (1.15±0.93 g/L), which are consistent with the results of other conventional RIA. The recovery, intra- and inter-assay coefficients of variation conform to the demands of RIA, and the results of 41 samples obtained by both the PSA RIA and PSA RIA of DPC were well correlated (=0.990). PSA level of 23 patients with prostatic carcinoma was 10400 g/L.     

Elements in car and truck tires and their volatilization upon incineration

The trace metal loading of used car and truck tires and the fractions of the metals volatilized upon incineration of the tire were determined. INAA was chosen due to its multielement analysis capability and its low detection limit for many elements. A high purity planar germanium detector was used. Among the elements measured were, Al (4–150 g/g), Ti (41–730 g/g), V (0.04–0.4g/g), Mg (>80–580 g/g), Zn (1–2.2%) as typical concentrations; also some amounts of antimony, bromine and arsenic have been found. Major differences in elemental concentrations have been observed between the tread and the wall of a tire, and also between different brands.     

Determination of Mg,Al, P,Cu and Mn in biological fluids by neutron activation analysis

Thermal and epithermal neutron activation analysis has been applied to determine the concentrations of magnesium, aluminium, phosphorus, copper and manganese in two biological fluids: blood serum and market milk. Both epithermal neutron irradiation and radiochemical separation (a chromatographic column of HAP) were used to get rid of the interferences from 24-Na. Strongly acidic solutions of the irradiated samples were passed through the columns of HAP, where sodium was completely adsorbed while, Al, Cu, Mg and Mn were eluted with an efficiency of 99±1%. Since both Al and P were determined through the formation of²⁸Al (2.24 min) thermal and epithermal neutron activation have been applied in order to determine the contribution of each radionuclide to²⁸Al activity. The determination of Mg, Al and P in milk samples was done instrumentally, whereas in the case of blood serum with higher concentration of Na, a radiochemical separation is essential in both cases. The concentrations of Al, Cu, Mg, Mn and P in blood serum and market milk were found to be 0.24±0.02 and 1.85±0.09 g Al/ml, 1.35±0.04 and 0.068±0.005 g Cu/ml, 22.9±1 and 98.9±8.6 g Mg/ml, 22±3 and 16±2 ng Mn/ml and 167±13 and 865±32 g P/ml, respectively.     

Differential determination of arsenic (III) and total arsenic with L-cysteine as prereductant using a flow injection non-dispersive atomic absorption device

Speciation of arsenic in environmental samples gains increasingly importance, as the toxic effects of arsenic are related to its oxidation state. A method was developed for the determination of trace amounts of arsenic(III) and total arsenic by flow injection hydride generation coupled with an in-house made non-dispersive AAS device. The total arsenic is determined after prereduction of arsenic(V) to arsenic(III) with L-cysteine in a low concentration of hydrochloric, acetic or nitric acid. The conditions for the prereduction, hydride generation and atomization were systematically investigated. A quartz tube temperature of 800°C was found to be optimum in view of peak shape and baseline stability. Pb(II), Ni(II), Fe(III), Cu(II), Ag(I), Al(III), Ga(II), Se(IV), Bi(III) were checked for interfering with the 2g/L As(V) signal. A serious signal depression was only observed for Se(IV) and Bi(III) at a 150-fold excess. With the above system, arsenic was determined at a sampling frequency of about 1/min with a detection limit (3) of 0.01g/L using a 0.5mL sample. The reagent blank was 0.001±0.0003 absorbance units and the standard deviation of 10 measurements of the 2 g/l As signal was found to be 1.2%. Results obtained for standard reference materials and water samples are in good agreement with the certified values and those obtained by ICP-MS     

Heterogeneous hydride generation in a packed membrane cell

Summary Volatilization of arsenic, selenium and antimony for sample introduction in atomic absorption spectrometry has been performed by pumping an acidic sample through an anion exchanger in the tetrahydroborate (III) form packed as a bed in the liquid channel of a gas-liquid separation membrane cell. The hydrides generated in the heterogeneous reaction between bound tetrahydroborate (III) ions and the analytes are rapidly transferred with the aid of the concomitantly generated hydrogen gas through the gas-permeable membrane into the gas phase and swept to the spectrometer by an additional hydrogen gas flow. This instant transfer of the hydrides to the gas phase kinetically discriminates the reaction of the hydride with metal borides and metal colloids, whose formation by reaction with tetra-hydroborate (III) is slower than the hydride reaction. The susceptibility to interference by transition metal ions is thus markedly reduced, as compared with both batch hydride generation methods and a previously presented heterogeneous reaction scheme. The detection limits for arsenic, selenium, and antimony were 1.2, 3.7, and 10 g/l, respectively. The calibration graphs were linear from the detection limit up to 125 g/l for arsenic, 150 g/l for selenium, and 250 g/l for antimony. The relative standard deviations at concentration levels of 10 and 100 g/l were 1.8 and 0.7% for arsenic and 2.3 and 1.2% for selenium. Corresponding figures for 50 and 100 g/l antimony were 2.5 and 1.6%.     

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.

     

Titrimetric determination of thiourea and silver with a picrate ion selective electrode

Summary A method has been developed for the semiautomatic potentiometric titration of thiourea with silver nitrate and of silver with thiourea, in the presence of picrate ions, using a picrate ion selective electrode. Thiourea in the range 15–1500g and silver in the range 200–1800g were determined with relative errors and relative standard deviation of about 1%.

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Zusammenfassung Eine halbautomatische potentiometrische Titrationsmethode für Thioharnstoff mit Silbernitrat bzw. umgekehrt in Gegenwart von Pikrationen mit Hilfe einer selektiven Pikratelektrode wurde entwickelt. 15–1500g Thioharnstoff bzw. 200–1800g Silber wurden mit einem relativen Fehler und einer relativen Standardabweichung von etwa ±1% bestimmt.

     

Colorimetric determination of vanadium with 5,7-dibromo-8-hydroxyquinoline after paper-chromatographic separation from interfering ions

Summary 5,7-Dibromo-8-hydroxyquinoline is recommended as reagent for the colorimetric determination of vanadium. The absorption is measured at 394 nm. Interfering ions are removed by paper chromatography with a collidine containing solvent. With amounts of 45–120 g of vanadium an error of ± 1 g has been obtained.

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Zusammenfassung Zur colorimetrischen Vanadiumbestimmung wird 5,7-Dibrom-8-hydroxychinolin als Reagens empfohlen. Die Messung erfolgt bei 394 nm. Störende Ionen werden durch Papier-Chromatographie mit einem collidinhaltigen Fliemittel entfernt. Der Fehler betrug ±1 g bei Vanadiummengen von 45–120g.

     

Development and application of a simple routine method for the determination of selenium in serum by octopole reaction system ICPMS

The aim of the study was to develop an inductively coupled plasma mass spectrometry (ICPMS) method for robust and simple routine determination of selenium in serum. Polyatomic interferences on ⁷⁶Se, ⁷⁷Se, and ⁷⁸Se were removed by applying an octopole reaction system ICPMS with the reaction cell pressurized with H₂ gas. We developed a novel simple optimization routine for the H₂ gas flow based on a signal-to-noise ratio (SNR) calculation of the selenium signal measured in a single selenium standard. The optimum H₂ flow was 2.9 mL min^–1. The selenium content in serum was determined after a 50-fold dilution with 0.16 M HNO₃ and quantified by using addition calibration and gallium as an internal standard. The method detection limit was 0.10 g L^–1 for ⁷⁶Se and ⁷⁸Se and 0.13 g L^–1 for ⁷⁷Se. Human serum samples from a case-control study investigating if selenium was associated with risk of colorectal adenoma were analyzed. The average selenium concentration for the control group (n=768) was 137.1 g L^–1 and the range was 73.4–305.5 g L^–1. The within-batch repeatability (a batch is ten samples) estimated from 182 replicate analyses was 6.3% coefficient of variation (CV), whereas the between-batch repeatability was 7.4% CV estimated from 361 replicates between batches. The method accuracy was evaluated by analysis of a human serum certified reference material (Seronorm Serum level II, Sero A/S, Norway). There was a fairly good agreement between the measured average of 145±3 g L^–1 (n=36) and the certified value of 136±9 g L^–1. In addition the method was successfully applied for analysis of zinc serum concentrations without further optimization. For the Seronorm certified reference material a value of 911±75 g L^–1 (n=31) for zinc was obtained, which corresponds well to the certified zinc value of 920±60 g L^–1.     

Bestimmung von Ascorbinsäure auf Grund ihrer in einem Landolt-System ausgeübten reduzierenden Wirkung

Zusammenfassung Im Bromat-Jodid-Ascorbinsäure-System hängt die Zeit, die bis zur Jodausscheidung vergeht, von der Konzentration der Ascorbinsäure ab. Unter entsprechenden Versuchsbedingungen ist die Reaktionszeit proportional der Ascorbinsäurekonzentration. Danach kann die Ascorbinsäure sowohl mit Hilfe der Simultankomparationsmethode, als auch chronometrisch bestimmt werden. Die Genauigkeit ist ± 3% im Bereich von 5 bis 300g/5 ml. Die Grenzen der Bestimmung sind 1g bzw. 1000g Ascorbinsäure in 5 ml.

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Determination of ascorbic acid on the basis of its reducing action in a landolt system

Summary In the bromate-iodide-ascorbic acid system, the time that elapses until the iodine appears is dependent on the concentration of the ascorbic acid. Under appropriate experimental conditions, the reaction time is proportional to the ascorbic acid concentration. Accordingly, the ascorbic acid may be determined with the aid not only of the simultaneous comparison method but also chronometrically. The precision is ± 3% in the 5–300g/5 ml range. The limits of the determination are 1g and 1000g ascorbic acid in 5 ml respectively.

     

On the use of azo dyes for the spectrophotometric determination of uranium and thorium in mixed solvents

Summary Solochrome Black 6 BN in an acetate buffered medium containing methanol reacts with U(IV) to give a blue complex which permits photometric determination with 5g U/ml to 100g U/ml.In the presence of zinc acetate, uranyl ion also may be spectrophotometrically determined by means of the same dye. From 2g U/ml to 40g U/ml may be determined with a relative error of less than ± 0.05.

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Zusammenfassung Es werden zwei Methoden zur spektrophotometrischen Bestimmung von Uran mittels Solochromschwarz 6 BN beschrieben. Dieser Farbstoff bildet mit U(IV) in acetatgepuffertem, methanolhältigem Medium einen blaugefärbten Komplex, der die Bestimmung von 5 bis 100g U/ml erlaubt.Mit demselben Farbstoff lassen sich auch 2 bis 40g U/ml in Lösungen von Uranylchlorid bestimmen.

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Résumé Le noir solochrome 6 BN en milieu tampon acétique contenant du méthanol réagit avec U-IV en donnant un complexe bleu qui permet le dosage photométrique de 5 g U/ml à 100 g U/ml.En présence d'acétate de zinc, on peut aussi doser l'ion uranyle par spectrophotométrie avec le même colorant. On peut doser de 2 g U/ml à 40 g U/ml avec une erreur relative inférieure à ± 0,05.

     

Redox Properties of Trinuclear Osmium Carbonylhydride Clusters with Unsaturated Ligands

Schemes of redox transformations were proposed for osmium carbonylhydride clusters: trinuclear (-H)Os₃(-CR = CHR')(CO)_{1 0} (R = R' = H, Ph; R = H, R' = Ph), (-H)₂Os₃(₃-L)(CO)₉ (L = C = CHPh, CHCPh), tetranuclear CpMnOs₃ (-CH = CHPh)(-H)(-CO)(CO)_{1 1}, and trinuclear Os₃(₃-C = CHPh)(CO)₉. Two-electron reduction of the trinuclear clusters results in elimination of the unsaturated ligand with preservation of the metal framework.     

Mercury determination by CV-AAS in wastewater and sewage sludge from a stabilization pond system

The mercury concentrations in wastewater and sewage sludge of a stabilization pond system have been evaluated. The system is built by three parallel facultative ponds followed by two systems of three maturation ponds in series. The samples of wastewater and sludge were digested using nitric acid and placed into a Parr-type bomb for 4 h at 110° C. Mercury was measured by Cold Vapour Atomic Absorption Spectrometry (CV-AAS) at 253.7 nm with sodium tetrahydroborate as reductant. The methodologies were checked with an USEPA quality control sample, a standard reference material from NIST and with another method of mineralization (cold mineralization) showing good results. Concentrations of mercury in wastewater between 1.47 ± 0.75 gl^–1 have been found at the entrance of the system and 0.74 ± 0.0 gl^–1 at the exit, while in sludge the results were between 0.29 ± 0.12 gkg^–1 in the facultative pond and 0.04 ± 0.02 gkg^–1 in the second maturation pond (exit).     

Trace uranium analysis of water from the south-west coastal region of India

Water samples collected from various sources along the south-west coastal region of India have been analyzed for trace uranium concentration. Fission track registration technique with the Dry method has been used for the analysis. Uranium concentration was found to vary from 0.28±0.01 g/l to 2.71±0.41 g/l and was higher in sea water than in well, river and tap water, respectively.     

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 fluorine in solids down to 120 μg/g by wavelength dispersive X-ray fluorescence spectrometry

An X-ray fluorescence spectrometric method is described for the determination of fluorine from percent level down to 120 g/g in fluoropolymers and in fluoride samples. The method is based on the measurement of the intensity of first order line for 30 seconds using a flow proportional counter and a multilayer AXO6 crystal (2d=5.52 nm). The calibration curves of first degree base polynomials are linear over the concentration range of 8000–120 g/g and of 48.92–76% measured. The precision and accuracy obtained for polymer samples in percent level of fluorine are up to ±0.5 and within ±1%, respectively. However, the precision () for trace concentrations is in the range from 8 to 20%. In most cases the accuracy is up to ±7%, ±5% and ±4% in the concentration range of 120–8000 g/g, 801–8000 g/g and of 120–400 g/g, respectively. The time needed to analyze one sample including calibration and regression analysis is about 8 minutes.     

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.