Determination of cadmium in water samples by co-precipitation and neutron activation analysis

Lanthanide (Ln) levels in plasma and tissues from colorectal patients and healthy subjects were determined by radiochemical neutron activation analysis. Results, precision, accuracy and sensitivity are presented and discussed. Mean plasma levels of La, Ce, Nd, Eu and Yb were significantly higher (p<0.01) in adenoma and adenocarcinoma patients compared to control subjects. Increasing concentrations of plasmatic La, Eu and Yb as well as Ln levels in tissue from healthy subjects, adenomatous polyps, and adenocarcinoma (ADK) patients were observed. Measured tissue levels of Ln were constantly higher in ADK and adenomatous polyps than in the adjacent normal tissues. These findings may reflect impaired calcium metabolism possibly involved in the early process of carcinogenesis leading to the development of ADK.Presented at the MTAA-8 Conference, September 16–20, 1991, Vienna, Austria.     

Determination of cadmium in environmental materials by fast neutron activation analysis

Cadmium is determined by activation analysis with fast neutrons, obtained by irradiation of a thick beryllium target with 14.5-MeV deutrons. Cadmium-111m, formed via the ¹¹²Cd(n, 2n)^111mCd and ¹¹¹Cd(n, n′)^111mCd reactions, is separated by liquid—liquid extraction with zinc dithyldithiocarbamate in chloroform and measured with a Ge(Li) γ-spectrometer. For low concentrations, cadmium is precipitated as cadmium ammonium phosphate after the extraction. NBS and BCR reference materials were analyzed: for concentrations between 3 and 500 μg g^?1, the relative standard deviation ranges from 5 to 3% The results obtained for sewage sludge are compared with those obtained by reactor neutron activation analysis.     

Determination of thallium in biological samples by thermal neutron activation analysis and low-level beta-counting

A procedure is described for the determination of thallium in complex biological matrices by thermal neutron activation analysis employing substoichiometric extraction of thallium(I) with 2-mercaptobenzothiazole (2-HMBT) at a pH of 7.5 into chloroform, and low-level beta-counting.     

Determination of thallium in environmental samples by activation analysis with fast reactors neutrons

A procedure is described for the determination of thallium in coal fly ash by fast neutron activation analysis using the reaction²⁰³Tl/n, 2n/²⁰²Tl. A 31 h reactor irradiatioon under cadmium cover at a fast neutron flux of 3.05×10¹² n.cm^–2.s^–1 is applied. The simple radiochemical separation involves a wet attack in acids followed by an extraction of Tl/III/into diisopropylether from 0.5M HBr. The radiochemical purity is sufficient for immediate -spectrometry. A value of 5.7±0.7 ppm is found in the NBS 1633a coal fly ash.     

Determination of picogram amounts of technetium in environmental samples by neutron activation analysis

A procedure for the determination of trace amounts of ⁹⁹Tc in filter paper and vegetation samples by neutron activation analysis has been developed. The procedure consists of the following major steps: (a) pre-irradiation separation of technetium from the sample and purification of the technetium fraction; (b) thermal neutron irradiation of the ⁹⁹Tc fraction to produce ¹⁰⁰Tc ; (c) post-irradiation separation and purification of ¹⁰⁰Tc from other activated nuclides: (d) counting of the 16-sec ¹⁰⁰Tc in a low-background β-counter.

The estimated detection limits for ⁹⁹Tc by this procedure with irradiations at a thermal neutron flux of about 5.10¹³ n cm^-2 sec^-1 are: 5.lO^-12g ⁹⁹Tc in filter paper samples, and 9. 10^-12 g ⁹⁹Tc in vegetation samples.     

Determination of elemental concentrations in environmental plant samples by instrumental neutron activation analysis

The intake of leafy vegetables in daily diet is very important to meet our nutritional needs. Vegetables provide the essential elements which are necessary and recommended for human growth. However, due to rapid industrialization and urbanization our environment becomes polluted and this affects the normal growth of agricultural products and composition of environmental species. The elemental concentrations present in the environmental samples are good indicators to assess the toxicological levels due to pollution affects. In the present work we have analysed several vegetable plant samples by instrumental neutron activation analysis to determine the elemental concentrations at major, minor and trace levels. The leafy vegetables like spinach, red leafy veagetable, pui, gourd leaf, lettuce and katoua were chosen as these are extensively consumed by local peple in eastern part of India. We have determined 15 elements in the above mentioned vegetable samples and some of these are essential elements and some are toxic elements. It was found that Na and K were present as major elements, Fe and Zn as minor elements and As, Ce, Cr, Co, La, Mo, Rb, Sc, Sm, Sr as trace elements. The concentration level of Cr was found to be higher than that of recommended value certified by WHO and National environment quality control for human consumption. The validation of our analytical results have been performed by the Z-score tests through the determination of concentrations of the elements of interest in certified reference materials.     

Determination of traces of lithium in biological, environmental and metal samples by neutron activation analysis

Summary Lithium in environmental, biological and metal samples was determined by neutron activation analysis via the⁶Li(n,)T and¹⁶O(T,n)¹⁸F reactions. The samples were converted to aqueous solutions either by dissolution or by digestion and their aliquots were irradiated in a nuclear reactor for 2 h. The irradiated sample solution, was placed in a ZrO₂ column on which the¹⁸F nuclide was adsorbed. Most of the coexisting nuclides²⁴Na,⁸²Br,³⁸Cl,⁶⁴Cu, etc. were separated by elution with pH 1 3 solution. The column was subjected to a Ge(Li) detector for-ray spectrometry. The lithium content in the sample was estimated from the¹⁸F activity obtained. The matrix effect can be eliminated by either strong dilution of the samples in aqueous medium or by the method of standard addition. Lithium can be determined with high precision and accuracy in sub-ppm samples.

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Bestimmung von Lithiumspuren in biologischen, Umwelt- und Metallproben mit Hilfe der Neutronenaktivierungsanalyse

Zusammenfassung Lithium wird über die Reaktionen⁶Li(n,)T und¹⁶O(T,n)¹⁸F bestimmt. Die Proben werden durch Auflösung oder Aufschluß in wäßrige Lösung übergeführt und im Reaktor 2 h lang bestrahlt. Die bestrahlte Lösung wird auf eine ZrO₂-Säule gegeben, wo die¹⁸F-Nuklide adsorbiert werden. Die meisten anderen Nuklide (²⁴Na,⁸²Br,³⁸Cl,⁶⁴Cu usw.) werden durch Elution mit Säurelösung pH 1 3 abgetrennt. Die-Spektrometrie erfolgt mit einem Ge(Li)-Detektor. Der Lithiumgehalt ergibt sich aus der¹⁸F-Aktivität. Durch starke Verdünnung oder durch das Standardzugabeverfahren kann der Matrixeffekt eliminiert werden. Lithium ist so mit hoher Präzision und Genauigkeit in sub-ppm-Proben bestimmbar.

     

Determination of trace level mercury in biological and environmental samples by neutron activation analysis

Sorptivity studies with Chelex 100 column indicated chloride to be the best medium for the sorption of mercury. A radiochemical separation procedure has been developed for the determination of mercury by neutron activation analysis utilizing sorption of mercury on Chelex 100. The method was checked with Orchard Leaves and Tuna Fish standards from the National Institute of Standards and Technology.     

Determination of bismuth in lead by neutron activation analysis

Neutron activation analysis for bismuth in lead was performed through the separation and measurement of²¹⁰Po, using two different extraction procedures. The reproducibility of the results was good for lead containing bismuth in higher concentrations. For high purity lead, variations in the bismuth content have been found by different analyses of the same sample, owing to inhomogeneity in the distribution of the Bi metal traces. An independent analysis of the same lead samples gave comparable Bi concentrations.     

Determination of cadmium by substoichiometric thermal neutron activation analysis

A rapid and selective method has been developed for the determination of cadmium in environmental samples by thermal neutron activation analysis, employing substoichiometric solvent extraction technique. Alcoholic solution of 2-mercaptobenzothiazole /2-HMBT/ has been used for the substoichiometric extraction of Cd/II/ from an aqueous solution of pH 7.0 into methyl iso-butyl ketone /MIBK/.     

Determination of bromine, chlorine and iodine in environmental aqueous samples by epithermal neutron activation analysis and Compton suppression

Summary Halides, particularly Br^- and Cl^-, have been used as indicators of potential sources of Na⁺ and Cl^- in surface water and groundwater with limited success. Contamination of groundwater and surface water by Na⁺ and Cl^- is a common occurrence in growing urban areas and adversely affects municipal and private water supplies in Illinois and other states, as well as vegetation in environmentally sensitive areas. Neutron activation analysis (NAA) can be effectively used to determine these halogens, but often the elevated concentrations of sodium and chlorine in water samples can give rise to very high detection limits for bromine and iodine due to elevated backgrounds from the activation process. We present a detailed analytical scheme to determine Cl, Br and I in aqueous samples with widely varying Na and Cl concentrations using epithermal NAA in conjunction with Compton suppression.     

Determination of lead and cadmium in biological samples by potentiometric stripping analysis

Summary The determination of lead and cadmium in biological materials was carried out by potentiometric stripping analysis. Supporting electrolyte was a mixture of NaCl and HCl. In the presence of 4% lumatom in methanol, oxidation potentials of –0.46 V for Pb and –0.68 V for Cd were found (vs. SCE). The method was applied to different standard reference materials (leaves, needles, hair) and was also compared with the differential pulse anodic stripping technique. The latter presented considerable difficulties, in particular by the interference of oxygen.

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Bestimmung von Blei und Cadmium in biologischem Material durch potentiometrische Stripping-Analyse

Zusammenfassung Als Trägerelektrolyt diente bei diesem Verfahren ein Gemisch von NaCl und HCl. In Gegenwart von 4% Lumatom in Methanol wurden Oxidationspotentiale von –0,46 V für Pb und –0,68 V für Cd (gegen SKE) erhalten. Die Methode wurde auf verschiedene Referenzmaterialien (Laub, Nadeln, Haar) angewendet und auch mit der Differentialpuls-Anodic Stripping-Analyse verglichen. Bei der letzteren ergaben sich größere Schwierigkeiten, hauptsächlich durch störenden Sauerstoff.

     

Determination of arsenic,cadmium and zinc in river water by neutron activation analysis

A concentration apparatus has been developed for the determination of As, Cd and Zn in water by neutron activation. The preconcentration technique used for this purpose is based on the retention of As, Cd and Zn on the Rexyn 201 resin at pH 10. The apparatus used minimizes the manipulations needed for preconcentration and contamination by trace elements present in reagents. Eleven samples of water from rivers in the Montreal region were analyzed and the following concentrations were found (in μg/1): As 0.86–1.95, Cd 0.61–0.98 and Zn 4.6–12.9.     

Determination of cadmium using radiochemical neutron activation analysis

A method has been developed for the determination of cadmium in samples of food and biological materials using neutron activation analysis with radiochemical separation. The irradiated sample is digested in presence of cadmium carrier, with a nitric-perchloric mixture, evaporated to dryness, dissolved in 6M HCl and placed onto an ion exchange column loaded with Dowex 1-X8 resin in chloride form and conditioned with HCl 6M. The cadmium is retained in the resin. After a washing procedure with several portions of HCl of decreasing concentration, the cadmium is eluted with an ammonia-ammonium chloride buffer. The activity of ^115mIn which is in equilibrium with ¹¹⁵Cd, is measured using a NaI(Tl) well type detector. The method has been evaluated by analyzing certified reference materials with cadmium concentrations covering a range of 0.020 to 200 mg^.kg^-1. The agreement of the results with the certified values is within 95%, which gives an indication of the sensitivity and accuracy of the proposed method.     

Possibilities of simultaneous determination of lead and thallium in environmental and biological samples by microtron photon activation analysis with radiochemical separation

A method for simultaneous determination of lead and thallium by photon activation analysis with radiochemical separation using irradiation with bremsstrahlung produced by a 20 MeV microtron is described. The detection limits for 500-mg samples of 0.9 g·g^-1 and 0.15 g·g^-1 for lead and thallium, respectively, were achieved that are sufficiently low for the reliable determination of both elements at levels commonly occurring in environmental samples and at elevated levels in biological materials. The accuracy of the procedure developed was proved by analyses of a number of environmental and biological reference materials. Possibilities of detection limit improvements are also discussed.     

Intercomparison and determination of environmental standard samples by instrumental neutron activation analysis

To identify and improve the analytical technique for air pollution research, four kinds of environmental standard samples, i.e., airbome particulate matter, coal flyash, soil and pine needle supplied from the NIST and the IAEA were analyzed using thermal and epithermal neutron activation techniques. Sample irradiation was done at the irradiation facilities (neutron flux, 1 · 10¹³ n·cm^–2·s^–1) of the TRIGA MARK-III Research Reactor in the Korea Atomic Energy Research Institute. The accuracy and precision for the analysis of 40 trace and toxic elements in the samples were compared with the certified and reported values, respectively. In the analytical results of all standard reference materials, the relative standard deviation were within the 15% except for 11 elements and the relative error were agreed within the 10–20% except for 13 elements. The benefit of epithermal activation was investigated and the optimum analytical condition is reported.     

Determination of rare earths in geological samples by neutron activation analysis

The significance of rare earth distribution patterns in trace element geochemistry is briefly reviewed. Established methods for their determination at the Reactor Centre by instrumental and radiochemical techniques are described, and examples of recent applications discussed.     

Determination of rare-earth eleemnts in rock samples by neutron activation analysis

A Ge(Li) detector combined with cation exchange separation has been used for the determination of 12 rare-earth elements (La, Ce, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu) in rock samples by neutron activation analysis. After purification by the conventional hydroxide-fluoride precipitation, the rare-earth elements are separated into two fractions, light (La-Tb) and heavy (Ho-Lu), by EDTA cation exchange, and the γ-activities of the two fractions are measured by a Ge(Li) detector. The heavy rare-earths, such as Ho, Er, and Tm, can be easily γ-counted without serious interference from the intense Compton background and photopeaks due to the light rare-earths such as¹⁴⁰La,¹⁵³Sm,¹⁵²Eu, and¹⁶⁰Tb. The chemical yields (60%) for the individual rare-earths are determined by a reactivation technique. The results obtained for the U.S. Geological Survey standard rocks G-1 and W-1 are compared with the previously reported data.     

U determination in environmental samples by delayed neutron activation analysis in Korea

A delayed neutron counting system has been implemented at the HANARO research reactor in 2007. Thermal neutron flux measured at the NAA #2 irradiation hole coupled to the delayed counting system, was higher than 3 × 10¹³ n cm⁻² s⁻¹. The delayed neutron counting system is composed of 18 ³He detectors which are divided into three groups with six detectors and the collected signals of each group are processed to a digital signal. The count numbers were measured with the uranium mass by using NIST SRMs under fixed analytical condition and their correlation could be determined. Finally, delayed neutron activation analysis has been carried out for the determination of uranium mass fraction in the collected environmental samples.     

Determination of copper in biological samples by substoichiometric neutron activation analysis

A method has been described for the determination of trace amounts of copper in biological samples by thermal neutron activation analysis, involving radiochemical separation of copper from irradiated matrix employing substoichiometric extraction of Cu/II/ with 2-mercaptobenzothiazole /2-HMBT/ into chloroform. 4.01 g of Cu/II/ can be determined with an accuracy of 3.13% and precision of 1.08%.