Substoichiometric determination of silver by Neutron Activation Analysis

A rapid and selective method has been developed for the determination of Ag in biological samples and mineral ores by thermal neutron activation analysis employing substoichiometric extraction with 1,2,3-benzotriazole /1,2,3-BT/ into chloroform. The time required for the radiochemical purification and counting of two samples was 1 h. 4.84 g Ag can be determined with an accuracy of 7.44% and a precision of 3.57%.     

Characterization of solar grade silicon by Neutron Activation Analysis

An analytical method using neutron activation was developed in order to orientate and check different silicon elaboration processes either as solid ingots or ribbon shaped. This method without chemical separation after irradiation implies the use of a high efficiency semiconductor detector. A particular attention was paid to different causes of error and to the detection limits really obtained. These limits range from 10⁹ to 10¹⁵ at.cm^–3 for about 30 elements systematically locked for after a 72-h irradiation.     

Instrumental Neutron Activation Analysis of Extractable

Instrumental neutron activation analysis was performed to measure the levels of extractable organohalogens (EOX) in the organisms from the Antarctic marine ecosystem. The results show that EOX (EOCl, EOBr and EOI) were found in all the samples analyzed. The highest concentration was determined in the ascidian sample. The concentration order of EOX was mainly EOCl>EOBr>EOI with the exception of nemertine, ascidian, fish and adelie penguin samples. The concentrations of man-made organochlorines (DDTs and CHLs) were analyzed by GC-MS, and the results were compared with the concentrations of EOX determined in the same samples. The results show that the contribution of known man-made organochlorines in EOCl was less than 3%. This means that a large amount of unknown organochlorine compounds is present in Antarctic marine organisms.     

Neutron Activation Analysis of Manganese Mercury Telluride

Procedure were proposed for the radiochemical neutron activation analysis of Mn _x Hg_1?xTe using an AV-17-HCl chromatography system for separating macro and micro components. Using a combination of procedures, one can determine 34 impurity elements in manganese mercury telluride at a concentration level of n × (10^?5?10^?10) wt %.     

中子活化分析测定牛奶中的有机卤族化合物

1　引　　言由于有机卤族化合物污染的普遍性和突出的“三致”作用 (致癌、致突变、致畸形 ) ,有机卤族化合物的环境行为一直是环境化学的研究热点 ,也是世界各国重点控制的污染物。有机卤族化合物的分析测定一直由色谱完成 ,但由于该类化合物有成千上万种 ,色谱分析不可能对样品中的所有有机卤族化合物进行定性和定量分析。有研究表明 :色谱分析结果只占实际污染水平的 1%～ 2 6% ,并不能准确反映有机卤族化合物的总体污染水平。中子活化分析 (ＮＡＡ)是目前唯一一种能同时定量测定有机Ｃｌ、Ｂｒ和Ｉ的方法。本工作用中子活化分析测定了牛…     

The Determination by Neutron Activation Analysis of Selected Elements in Cigarettes

Abstract

Neutron activation analysis was used for the determination of Na, Al, CI, K, Ca, Sc, Mn, Cu, Br, and La in the tobacco, mainstream smoke condensate, paper, and dropped ash of the Kentucky Reference Cigarette (IRI). The procedure requires no sample transfers prior to activation and no radiochemical separations before counting.     

Nondestructive Determination of Mercury in Copper by Thermal Neutron Activation Analysis

Abstract

Thermal neutron activation analysis was applied to the nondestructive determination of parts per billion (p.p.b.) quantities of mercury in high purity, oxygen-free high conductivity (OFHC) copper. The data were treated to a five-point gamma spectrum smoothing to reduce the statistical variations due to the low count rates. Linear regression and a statistical evaluation of the data were also performed. Net photopeak counting rates of approximately 43 counts per minute (c.p.m.), compared to a background of approximately 6 c.p.m., were obtained for six two-gram copper samples containing 38 ± 12 p.p.b. mercury.     

The determination of molybdenum in geological samples by Neutron Activation Analysis

A metal-silicate extraction technique combined with neutron activation analysis has been developed to determine molybdenum in geological samples. The samples are equilibrated with Femetal powder at high temperatures. Molybdenum is completely extracted into the metal phase because of very reducing conditions in the furnace. The metal spherule is separated from the silicates, irradiated and dissolved in an acid solution. The molybdenum is precipitated as a sulfide and the precipitate is dissolved in aqua regia and counted on a Ge/Li/detector. The radiochemical yield is obtained by irradiation of the solution. The method avoids production of⁹⁹Mo from induced fission of²³⁵U by performing the metal-silicate separation before irradiation. The precipitation step may be necessary to remove the high background from the decay of⁵⁹Fe. Mo concentrations down to 15 ng/g have been obtained using this method.     

Determination of platinum distribution in adenocarcinoma black-mice by Neutron Activation Analysis

30 female C57 bl. mice were treated with Adenocarcinoma im. in the right hind leg. Three days later cis-dichlorodiamine platinum was applied orally /15 mg/kg/ to all animals and additional 0.05 mg Prednisolone i.p. to 20 animals. Tissue samples from bloods, livers, kidneys, spleens, hearts, lungs, tumors and gastrointestinal tract were analyzed for their Pt concentration after therapy with cis-dichlorodiammine platinum complexes and Prednisolone by instrumental neutron activation analysis. Even 5 animals were sacrified. The amount of Pt in most of the organs examined remained under 0.05% of the quantity applied. Maximum values were detected at the end of the experiment, except for the gastrointestinal tract, the liver and the kidneys. Treatment of the animals with Prednisolone did not produce a significant different distribution of Pt. Only in tumor tissues a significantly higher amount of Pt was observed after Prednisolone treatment at 48 h but not at 72 h. Blood levels increased with time after Prednisolone treatment, without Prednisolone blood levels decreased.     

中子活化分析测定油菜叶绿体中的微量元素

１　　引　　　　言微量元素如锰、铁和铜在植物光合作用中起重要作用,其在叶绿体中的含量与赋存状态已被广泛研究,但对叶绿体中其它微量元素的含量及对光合作用的影响研究较少。近年来,大量实验证明稀土元素能提高植物光合作用的能力,但叶绿体中是否含有稀土元素还不清楚。本工作分离并纯化了油菜的叶绿体,用中子活化分析测定了包括８个稀土元素在内的１９种微量元素的含量。２　　实验部分２．１　　仪器与试剂　　ＤＬ－７Ａ冷冻离心机（中国科学院武汉科学仪器厂）,７２１分光光度计（上海精密科学仪器有限公司）,高纯锗探测器及…     

Determination of Trace Molybdenum in Biological Matrices by Neutron Activation Analysis

Based on consecutive extractions using bismuth diethyldithiocarbamate and thallium diethyldithiocarbamate as reagents, molybdenum was selectively and highly enriched from biological matrices, and then subjected to neutron activation analysis. Most of interfering elements, e.g., Na, K, Br, P, Fe, U, etc. were simultaneouly removed and the preconcentrated samples always showed only the r rays from molybdenum after neutron bombardment. Thus, molybdenum in the biological matrices could be accurately determined.     

Neutron Activation Analysis of Samples of Unknown Composition

The advantages of relative analytical methods over absolute methods for calculating element concentrations have been demonstrated. A procedure for the neutron activation analysis of samples of unknown composition was proposed based on the numerical simulation of the gamma spectra of test samples.     

Determination of Trace Elements in Liquid Fuels by Instrumental Neutron Activation Analysis

Abstract

An instrumental neutron activation analysis with Ge(Li) γ -spectrometry and computer-assisted data reduction, has been developed for the determination of more than 20 elements in different liquid fuels. Organo-metallic standard solutions were mixed to obtain suitable standards. Two neutron irradiations and 4 γ-spectrometric measurements are required for each sample. Corrections were taken into account for a few spectrometric and nuclear interferences. The overall standard deviation for nearly all elements is mainly determined by counting statistics. The following elements can be determined : Na, Al, S, Cl, K, Sc, V, Cr, Fe, Co, Ni, Cu, Zn, As, Se, Br and La whereas the concentration of the following elements are mostly near the limit of detection: Mg, Mo, Sb, Ba, Th and Hg.     

Biotransformation of Implanted Coral in Some Animals Studied by Neutron Activation Analysis

In vivo behavior of biomaterial is dependent on the site of implantation. Characterization by atomic element transfers versus the implantation duration is a quantitative approach to the phenomenon. Here, bioactive coral is implanted in ovine, porcine and rabbit thighbones and not in sheep jawbones as previously reported. Biopsies extracted between 1 and 24 weeks are analysed by fast neutron activation. Mineral composition of the coral is greatly modified: Ca, P, Mg and Sr concentrations become comparable to those of mature bone some months after the implantation. Results suggest a bioactive resorption followed by apatite formation.     

Determination of Trace Elements in Tea and Coffee by Neutron Activation Analysis

Thermal neutron activation analysis, a high-resolution Ge(Li) gamma-ray spectrometer, and an IBM 360/67 digital computer were used to determine the concentration of Na, K, Sc, Cr, Mn, Fe, Co, Cu, Zn, Se, Br, Rb, Sb, Cs, and Hg in ground coffee and tea. This nondestructive multielement technique requires neither pre- nor postirradiation chemistry and eliminates problems of reagent contamination. The method is simple, precise and sensitive to 15 elements. Interferences from fast neutron (n, p) and (n, α) reactions are small and, if necessary, corrections may be applied easily. This technique can be applied to percolated tea and coffee.     

南极岩石样品中稀土元素的中子活化分析

用仪器中子活化分析技术,测定了南极岩石中8种稀土元素含量,讨论了不同岩石的稀土模式特点。     

The Determination of Co in Plant Materials by Radiochemical Neutron Activation Analysis

The influence of irradiation conditions on the results of Co determination in plant samples by radiochemical neutron activation analysis (RNAA), after the conventional and microwave assisted wet digestion, has been investigated. Nine CRMs of botanical origin were examined. The study has demonstrated that the effectiveness of mineralization depended significantly on the kind of sample and the irradiation conditions. When analyzed CRMs were subjected to long-term irradiation in a high neutron flux, the mineralization using the microwave technique was necessary to obtain the correct results of Co determination in some of the plant samples. It has been proved that microwave digestion in a mixture of HNO₃+H₂O₂+HF should be a standard method of wet ashing, independent on matrix and irradiation conditions.