Routine determination of mercury,arsenic and selenium by radiochemical Neutron Activation Analysis

A method for the determination of mercury, arsenic and selenium by neutron activation analysis is described. Radiochemical separations are performed by selective distillation followed by electrolysis of mercury on gold and precipitation of arsenic and/or selenium by reduction to the elemental form. The chemical yields are 80–90% for mercury and 90–100% for arsenic and selenium. Interference tests have been carried out with reference to those elements most likely to interfere with the analysis. Detection limits for mercury, arsenic and selenium using 0.1 g of sample are 0.2 ng g^–1, 2 ng g^–1 and 3 ng g^–1, resp. Detection limits can be improved using greater sample size and neutron flux density. Results from the analysis of several NBS standard reference materials are given.     

Cold vapor atomic absorption spectrometric determination of mercury using sodium tetrahydroborate reduction and collection on gold

Summary Sodium tetrahydroborate(III) is equivalent to or better than tin(II) chloride as a reducing agent for mercury in cold vapor atomic absorption spectrometry using collection on gold. Concentrations of copper, silver, nickel, iodide, antimony, arsenic, bismuth and selenium typically found in water or waste water do not interfere. Prerequirements for satisfactory performance are that the gold is at a temperature below 100C during collection of mercury and that the gas from the reaction flask is washed with sodium hydroxide and dried with magnesium perchlorate. All determinations were carried out in 5 mol l^–1 hydrochloric acid and in the presence of 200 mg l^–1 iron(III). Detection limits (3) of 0.15 ng absolute, and of 15 ng l^–1 or 3 ng l^–1, using 10 ml or 50 ml solution, respectively, are obtained. The analytical curve is linear to 40 ng, and the relative standard deviation in the optimum working range is better than 2%.

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Kaltdampf-Atomabsorptionsspektrometrische Bestimmung von Quecksilber mit Reduktion durch Natrium-Tetrahydroborat und Sammeln auf Gold

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Dedicated to Prof Dr. W. Fresenius on the occasion of his 75th birthday     

A neutron activation analysis of selenium,arsenic and antimony in rocks and sediments by simultaneous evolution with bromide-strong phosphoric acid reagent

A rapid and sensitive method for the neutron activation analysis of selenium, arsenic, and antimony is described. These elements and their compounds present in rocks and sediments were simultaneously evolved as their gaseous bromides from sodium bromide-strong phosphoric acid medium only by heating the irradiated samples in the medium. The evolved gas was absorbed in an appropriate absorption solution and then each element was finally recovered as metals for selenium and arsenic, and as sulphide for antimony. The preferable conditions for the distillation and for the separation of these elements are discussed. The method thus established was applied for the activation analyses of rocks and of river sediments, and profitable data were obtained. Part of this work was performed at the Research Reactor Institute, Kyoto University.     

化学蒸气发生-四通道原子荧光光谱法同时测定水样中的痕量砷、锑、硒和汞

应用自行设计的化学蒸气发生-四通道无色散原子荧光光谱仪,建立了同时测定水样中As、Sb、Se、Hg的新方法.在实验中优化了四元素同时化学蒸气发生条件和测定的最佳工作参数.在样品预处理阶段用HCl将Se6+还原为Se4+,然后用质量浓度5 g/L硫脲将As5+和Sb5+还原为As3+和Sb3+.在最佳条件下,方法对As、Sb、Se、Hg的检出限分别为0.05、0.03、0.05、0.01 ng/mL(3d);RSD分别为0.42%、0.74%、0.97%、1.0%(对5 ng/mL As、Sb、Se和0.5ng/mL Hg混合标准,n=7).用所建立的方法对不同类型水样中的As、Sb、Se、Hg进行了同时测定,测定结果与用标准方法测定所得结果之间无明显差异,各元素的加标回收率在93%～105%.     

Radiochemical activation analysis of arsenic,selenium and antimony in biological samples

A method for the neutron activation analysis of arsenic, selenium and antimony has been developed. A radiochemical separation is performed by distillation followed by precipitation of the individual elements. Selenium and arsenic are precipitated by reduction to the elemental form while antimony is precipitated as sulfide. The chemical yields and detection limits using 0.5 g samples are the following: As 90–100%, 0.4 ppb, Se 80–100%, 8 ppb and Sb 50–70%, 0.2 ppb. Results from the analysis of nine international biological standard samples are given.     

Determination of Au,Sb, As,Br, Na,K, Cd,Mn and Cl in rice from Vietnam by neutron activation analysis

Gold, antimony, arsenic, bromine, sodium, potassium, cadmium, manganese and chlorine were determined by neutron activation analysis in various rice seed, brand layer and husk from Vietnam. The following concentration values were found: Au 0.05–0.28 ppm, Sb 0.05–1.08 ppm, As 0.08–0.94 ppm, Br 0.82–6.72 ppm, Na 16.71–25, 71 ppm, K 2582–5163 ppm, MN 19.26–33.43 ppm, Cd 0.51–2.42 ppm and Cl 205.20–828.61 ppm in rice seed. These elements were also determined in brand layer and rice husk. Statistically significant differences /t=0.05/ in Au, Sb, Cd contents were detected in rice seed and rice husk, as well as brand layer with rice husk.     

Determination of Trace Elements in Arsenic and Antimony Minerals by Atomic Absorption Spectrometry and k0-Instrumental Neutron Activation Analysis After Removal of As and Sb

The content of trace elements in arsenic and antimony minerals from the Allchar mine, Macedonia, was determined by electrothermal atomic absorption spectrometry (ETAAS) and k₀-instrumental neutron activation analysis (k₀-INAA) after removal of arsenic and antimony. Their direct determination by ETAAS or k₀-INAA in arsenic (realgar and orpiment) and antimony (stibnite) minerals is limited by strong matrix interferences from As and Sb. Successful elimination of both elements was realized by the extraction of their iodide complexes into toluene. It was found that the optimal conditions were triple extraction of arsenic into toluene from 6mol·L^–1 HCl with addition of KI. Triple extraction of antimony was most successful in the system 4.5mol·L^–1 H₂SO₄ and KI into toluene. In both cases, trace elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were then detected in the aqueous phase by ETAAS. The proposed procedures with ETAAS were checked by the method of standard additions and Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn determined in realgar, orpiment and stibnite. Using k₀-INAA the trace elements Ba, Ce, Co, Cr, Cs, Fe, Hg, Sc, Tb, Th, U and Zn in realgar and orpiment were determined before and after As and Sb removal from the same aliquot of sample. The removal of both elements with KI into toluene was higher than 99.8% and no losses of trace elements were observed.     

Activation analysis of selenium in organic samples,through selenium-77m,on a pre-separation basis

A method is described to separate trace amounts of selenium in organic samples without using a carrier, based on the adsorption on active carbon filters of the complex formed with APDC at pH 1.5. The separation is made prior to the neutron irradiation and the correction for selenium in the reagents performed by the irradiation of a blank. The method has been successfully used in fodder samples as well as some other organic reference materials, using a fast pneumatic transfersystem, which takes the samples from the irradiation position to the counting position in 3s, with the only limitation of the thermal neutron flux available, 4.7·10¹¹ cm^–2·s^–1. Detection limits of 0.1 g are obtained under these experimental conditions.     

Purity control of aluminium metal

As a contribution to the neutron activation assay of the reactor grade aluminium, a number of elements have been investigated by a developed analytical scheme. With the performance of ion-exchange chromatography combined with the precipitation techniques, ppm concentration (or even less) of arsenic, antimony, calcium, copper, mercury, selenium and strontium contaminants were demonstrated with good reproducibility. Whenever possible, some of the elements analyzed by radioactivation and proved to be present in high concentration levels were assayed by other standard analytical methods.     

INAA for control of technology in producing Mo and W

INAA technique for the determination of impurities (O, F, Na, Mg, Al, Si, P, S, K, Sc, Cr, Mn, Fe, Co, Ni, etc.) and of some doping elements in molybdenum and tungsten with detections limits between 10^–12 and 10^–6g/g by using a nuclear reactor and a neutron generator have been developed. The methods have been used to control the products of processing of refractory materials, to study the dynamics of impurities and doping elements at all stages of the production process.     

The Simultaneous Arsenic,Antimony, and Selenium Determination in Water Samples by Batch Hydride Generation Atomic Absorption Spectrometry

The purpose of this paper is to present a procedure for the simultaneous determination of metalloids: arsenic, antimony, and selenium. Hydride generation was provided in a reaction vessel connected with the atomic absorption spectrometer (AAS) in a fast sequential mode. Two different types of water samples were used while developing the application: seawater and groundwater. The methodology of liquid samples analysis was developed with detection limits of 0.05, 0.03, and 0.06 ng · mL^?1 for arsenic, antimony, and selenium, respectively, in 10 mL samples. This methodology was used to determine arsenic, antimony, and selenium in natural water samples.     

Comparison of neutron activation analysis with conventional detection techniques for the evaluation of trace elemental contamination in Mallard (<Emphasis Type="Italic">Anas platyrhynchos</Emphasis>) feathers

Instrumental neutron activation analysis (INAA) was used to determine trace elemental contamination in bird feathers. Primary feathers from twelve mallard (Anas platyrhynchos) ducks, migrating through the Thousand Islands region of Ontario, Canada, were analyzed for selenium, mercury, chromium, arsenic and antimony. Certified reference materials were used to assess the quality of the analytical procedure. Quantification of chemical elements was performed using Ortec Gamma Vision software. Five chemical elements were quantified, with corresponding analytical uncertainties of less than 20%. Results indicated the presence of As (max = 0.13 mg kg⁻¹), Cr (max = 2.6 mg kg⁻¹), Hg (max = 7.7 mg kg⁻¹), Sb (max = 0.31 mg kg⁻¹) and Se (max = 1.31 mg kg⁻¹). To assess the validity of using INAA as a quantitative analytical technique for feather samples, two standard reference materials were examined and mercury results were compared to those obtained from both direct mercury analysis (DMA) and cold vapour atomic absorption spectroscopy (CVAAS). Several CVAAS results differed significantly from the INAA results; in many instances CVAAS appeared to under-report when compared to INAA, with relative percent difference values as high as 126%. Conversely, results obtained using DMA compared favourably with INAA. For all samples, RPD values were within 30%. This is the first study to use INAA to examine feather contamination in Canadian migratory waterfowl and the first to corroborate INAA feather results by comparing them to those obtained using CVAAS and DMA.     

Selenium and mercury determination in biological samples using gamma–gamma coincidence and Compton suppression

Biological materials containing trace amounts of mercury and selenium were examined using neutron activation analysis. They were analyzed using Compton suppression and γ–γ coincidence counting. The 279 keV photopeak of activated mercury (²⁰³Hg) was analyzed in order to observe the mercury content in these samples. Selenium, an element found in many biological samples, interferes with the analysis of ²⁰³Hg when activated (⁷⁵Se). Because the selenium interference comes from a cascading emission, Compton suppression was utilized to reduce this interference. In order to fully characterize the selenium content in the samples, γ–γ coincidence was used which reduced the background and eliminated bremsstrahlung interference produced from neutron activated phosphorous through the ³¹P(n, γ)³²P reaction which is a pure beta emitter. As a result, we determined the mercury and selenium concentrations in three standard reference materials, which contain varying ratios of mercury to selenium concentrations. This study also showed that these types of concentrations can be determined from small (<500 mg) sample masses. Further work needs to be done on wet samples that require dehydration, as mercury can be lost through this process.     

Removal of exogenously bound elements from human hair by various washing procedures and determination by inductively coupled plasma mass spectrometry

A review of the literature shows that a variety of washing procedures to remove external contamination from hair have been proposed, but as yet no standardised procedures are available. In this study, methods for the pre-treatment and determination of antimony, arsenic, cadmium, chromium, lead, mercury and selenium in human hair by inductively coupled plasma mass spectrometry (ICP-MS) are developed.Investigations of various washing procedures to remove external contaminants show that in unexposed hair samples cadmium, lead and mercury are significantly removed from hair using a 0.1 M HCl wash, with 87, 73 and 5%, respectively being washed-off. The removal of antimony, arsenic and chromium from unexposed hair is, however, more efficient with 1% (v/v) sodium lauryl sulphate (SLS), with 43, 40 and 13% of each element, respectively being washed-off. Selenium is not removed from the hair by any of the washing methods studied. For the digestion of hair samples a digestion mixture of nitric acid and hydrogen peroxide is used.Experiments with simulated sweat spiked with each of these elements show that exogenously bound chromium, cadmium and lead are removed after washing with 0.1 M HCl. In contrast, antimony, arsenic, selenium and mercury irreversibly bind and, thus, are not removed with any of the washing solutions investigated. This work also compares hair levels of these elements in an unexposed and exposed group using the method developed.     

Aktivierungsanalytische Bestimmung von Spurenelementen in Steinmeteoriten

Zusammenfassung Es wird ein Arbeitsgang beschrieben, der es gestattet, die Spurenelemente Selen, Arsen, Antimon, Zinn und Quecksilber in Meteoriten und Mineralen nach einer vorhergehenden Aktivierung im Core eines Reaktors und nach Destillation ihrer Halogenide aus der Matrix voneinander zu trennen und quantitativ zu erfassen. Aus dem Destillat wird dazu vorerst aus starker Salzsäure das Selen mit Schwefeldioxid gefällt. Die weitere Trennung erfolgt über einen Anionenaustauscher Dowex 1-X8. An diesem werden Antimon, Zinn und Quecksilber adsorbiert, während Arsen im Effluenten als Arsentrisulfid gefällt und gemessen wird. Für die Trennung der am Austauscher adsorbierten Elemente Antimon, Zinn und Quecksilber werden zwei Arbeitsmethoden diskutiert. Nach der einen wird Antimon mit 10%iger Ascorbinsäure in 0,4 n HCl eluiert, nach der anderen weit vorteilhafter mit 10%iger Ammoniumnfluoridlösung, die 0,5 n an HCl ist. Anschließend wird in beiden Fällen Zinn mit 22 n H₃PO₄ und Quecksilber mit mindestens 7 n HNO₃ eluiert. Für den Trennungsgang wurden auch die Ausbeuten radiochemisch bestimmt.

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Summary A method is described for the isolation of trace quantities of selenium, arsenic, antimony, tin, and mercury from meteorites and minerals after preliminary activation of the samples in a reactor core followed by the distillation of the halides from the matrix materials. In the distillate selenium is first precipitated in the presence of strong hydrochloric acid using sulphur dioxide as reducing agent. Further separation is effected on the anion exchanger Dowex 1-X8. On this resin antimony, tin and mercury are retained while in the effluent arsenic is precipitated as trisulphide and then subjected to measurement. For the separation of the adsorbed elements antimony, tin and mercury two different techniques are discussed. In one case antimony is eluted with aqueous 10% ascorbic acid solution 0.4 N in hydrochloric acid and in the other, which appears to be more advantageous, an aqueous 10% solution of ammonium fluoride 0.5 N in hydrochloric acid is employed. Subsequently in both cases tin and mercury are removed from the resin using 22 N orthophosphoric acid and nitric acid (normality not below 7 N), respectively. The recoveries of this separation method have also been determined radiochemically.

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The research reported in this document has been sponsored by the United States Government under Contract 61(052)-948.     

Radiochemical Neutron Activation Analysis of Rhenium and Ammonium Perrhenate Samples

A procedure for the radiochemical neutron activation analysis of rhenium and ammonium perrhenate samples was developed. The procedure provides the determination of about 30 impurity elements present in concentrations of n× 10^–4to n× 10^–8mass % with RSD of 20–30%. An AV-17 anion exchanger–nitric acid solution system was used, which allows the selective separation of rhenium from a wide variety of elements.     

Neutron activation analysis of traces in electrolytic zinc sulphate solutions : Part III. Simultaneous determination of tellurium,selenium, arsenic and antimony

A neutron activation analysis is described for the simultaneous determination of tellurium, selenium, arsenic and antimony in an electrolytic zinc sulphate solution. The activity induced in the tellurium was measured by means of its radioactive daughter ¹³¹I. The chemical separation of iodine was performed by extraction into carbon tetrachloride. The interference due to the fission of uranium was minimised by a preseparation of uranium. The isotope ⁷⁵Se was measured by a γ, γ-coincidcnce technique, which allowed the determination of 0.002 μg Se/ml. Selenium was chemically separated by extraction as piazselenol. Arsenic and antimony were separated by precipitation as sulphide and distillation as chloride. The isotopes ⁷⁶As and ¹²²Sb were measured γ-spectrometrically, amounts of 0.02 μg/ml being determined. The method is also suitable, although not very sensitive, for the simultaneous determination of tin and germanium.     

Atomic absorption spectroscopic determination of arsenic in antimony compounds using solvent extraction and arsine generation

Summary An arsine generation-atomic absorption spectroscopic method for the determination of 0.04–4000 p. p. m. of arsenic in antimony compounds is described. The interference from antimony and other elements is eliminated by solvent extraction with benzene. The sample is dissolved in concentrated hydrochloric acid and reduced with titanium(III) chloride. Arsenic(III) is extracted into benzene from 10–12N hydrochloric acid at which concentration no antimony (III) is extracted; arsenic(III) is then back-extracted into water. Arsine is generated with potassium iodide, tin(II) chloride and zinc powder from 2.4N hydrochloric acid solution, and introduced to a nitrogen-hydrogen flame. The method has been tested with various antimony samples.

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Zusammenfassung Für die Bestimmung von 0,04–4000 ppm Arsen in Antimonverbindungen wurde ein Verfahren zur Arsinbildung und Atomarabsorption entwickelt. Die Störung durch Antimon und andere Elemente wurde durch Extraktion mit Benzol beseitigt. Die Probe wird in konz. Salzsäure gelöst und mit Titan(III)chlorid reduziert. Arsen(III) wird aus 10–12N Salzsäure mit Benzol extrahiert, ohne daß Antimon(III) mitextrahiert wird; As(III) wird dann in Wasser rückextrahiert. Mit Kaliumjodid, Zinn(II)chlorid und Zinkpulver wird aus 2,4N salzsaurer Lösung Arsin entwickelt und in eine Stickstoff-Wasserstoff-Flamme geleitet. Das Verfahren wurde mit verschiedenen Antimonproben getestet.

     

Instrumental neutron activation determination of Pt, Ru, Ir, Sc, Cr, Fe, Co, La, Ce, Nd, Sm, Yb, Lu, Hf and Ta employing CIRUS reactor as a thermal neutron source

An accurate and simple method has been developed for the determination of Pt, Ru, Ir and other elements employing instrumental neutron activation analysis (INAA). Nondestructive analysis has been carried out for the determination of these elements in different rock samples such as Dolerite, Dyke Dolerite, Country Basalt, Hyaloclastite, Trachyte, Ijolite, Spillite, Diorite and Lamprophyre from various locations like Daman, Tapti, Murud, Talasari, Ranala and Bassein in Maharashtra state. High flux provided by the CIRUS reactor (1×10¹³ n cm^–2s^–1) has been used for thermal neutron bombardment followed by radioassaying of the (n,) products on a HPGe detector coupled to a PC-based MCA unit.     

Separation of fluoride ion by extraction with triphenyltin chloride. Application for NAA of fluorine by means of 14-MeV neutrons

The separation of fluoride by extraction with toluene solution of triphenyltin chloride has been studied. Quantitative isolation of fluoride from solutions with a wide acidity range (pH 4.0–11.5) has been established. It is suggested that interferences by Ca, Mg, Fe, and Al can be avoided by masking these elements using sulfate and hydroxyde ions. Interference by phosphate ions can be overcome in a similar fashion. The halogenated species can be masked by mercury nitrate. Detection limit for fluorine determination is about 3 g for a neutron generator flux of 2·11¹¹ n·cm^–1·s^–1. A method for fluorine assay in water using a neutron generator with a detection limit of 1 ppm has been developed.