Instrumental activation analysis of vegetable tissue

A non-destructive method for the determination of bromine, manganese, phosphorus, potassium, sodium and zinc in plant tissue by neutron activation and gamma-ray spectrometry is described. Phosphorus and potassium have been determined also by beta-counting. The method should be especially attractive for analysis of manganese and zinc.     

The use of standards for quality control in activation analysis

The control of analytical data by randomly inserted standards or reference materials is quantified in terms of elementary statistics. The consequences of a given number of standard aliquots are interpreted on the basis of the a priori expectation on the average defective fraction. It appears that, in most cases, standards serve to detect sudden large errors only. Some practical examples are considered.     

The application of monitors in neutron activation analysis

The character and values of corrections are discussed which are required in the application of monitors (in particular, copper monitors) for the activation analysis of copper, zinc and manganese in biological samples.     

The application of photon activation analysis for the characterization of uranium minerals

Instrumental photon activation analysis can be used advantageously for the homogeneity control and the determination of uranium concentration in minerals and ores to be certified as uranium reference materials. The homogeneity control of high contents of uranium can also be performed by passive gamma-ray spectrometry with high energy resolution. Interferences of²³⁷U characteristic lines with gamma-rays from other radionuclides produced in the 44 MeV bremsstrahlung are evaluated.     

Quality control in activation analysis

Analytical quality control is needed to ascertain the reliability of results from all types of analysis, including activation analysis. Thea priori precision has to be combined with the statistics of counting in order to reach a state of statistical control. The Analysis of Precision is used to verify the absence of unknown sources of variability and to ascertain the absence of systematic biases or calibration errors by analyzing samples or reference materials with accurately known content or actual samples by an independent method.     

A modified cyanogen bromide method for the determination of nicotinic acid in vegetable foodstuffs

Summary The cyanogen bromide-aniline hydro chloride system for the determination of nicotinic acid in foodstuffs has been systematically studied, and a simplified and rapid procedure for the estimation of the vitamin has been developed.

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Zusammenfassung Die Bestimmung von Nikotinsäure in Nahrungsmitteln mit Hilfe von Bromcyan und Anilinchlorhydrat wurde systematisch überprüft. Ein vereinfachtes und rasches Verfahren zur Ermittlung des Vitamingehaltes wurde ausgearbeitet.

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Résumé On a fait l'étude systématique de l'emploi du mélange bromure de cyanogène-chlorhydrate d'aniline pour le dosage de l'acide nicotinique dans les substances alimentaires et l'on a mis au point un procédé simplifié et rapide pour l'estimation de la vitamine.

     

Role of activation analysis for radiation control in accelerator facilities

Activation is one of the severe problems at the high-energy accelerator facilities. By using gamma-ray spectrometry and activation detector technique, we could obtain important information on (1) nuclear reactions, (2) energy spectra of secondary particles, (3) penetration behavior of secondary particles in shield wall, (4) historical record of beam loss occurred in the accelerator rooms. It was concluded that the technique and knowledge of activation analysis are very useful to solve the radiation protection problems at the accelerator facilities.     

The application of cherenkov counting in 14 MeV neutron activation analysis

The conventional method of measurement in 14 MeV activation analysis is to employ gamma-ray spectrometry. The method has the advantage of good selectivity but this is at the expense of sensitivity. In order to improve sensitivity the authors have employed Cerenkov counting techniques and by the careful use of absorbers in a specially designed cell together with double decay procedures have still retained a considerable degree of selectivity. The method has been applied to neutron flux measurement and to the majority of the elements in the periodic table.     

The application of instrumental neutron activation analysis for the certification of the new NIST Fly Ash SRM

The National Institute of Standards and Technology (NIST) recently released the second renewal of its Trace Elements in Coal Fly Ash Standard Reference Material (SRM 1633b). This new material is currently certified for 23 major, minor and trace elements, and concentrations of an additional 24 elements are provided for information only purposes. Current plans are to certify the concentrations of a number of rare earths upon completion of additional analytical work now in progress. Instrumental neutron activation analysis (INAA) has played a major role in the certification of this new material in view of its potential for accuracy, multielemental capability, ability to assess homogeneity, high sensitivity for many elements, and essentially blank-free nature. For an element to be certified in a NIST SRM its concentration is usually determined by at least two independent analytical techniques. INAA has provided analytical information for 15 of the 23 elements certified, as well as for 22 of the 24 elements listed for information only. In addition, INAA has provided much of the homogeneity information for this SRM. This paper will describe these analytical procedures, and highlight those designed to optimize and assess the accuracy of the INAA measurements.     

The application of a252Cf neutron multiplier for routine instrumental neutron activation analysis

The successful application of instrumental neutron activation analysis for routine determinations depends on the ability to produce accurate and precise analytical results in a relatively short time. An important factor in obtaining the desired speed has been the availability of a low-cost, moderate-flux neutron source for on-site use. The²⁵²Cf neutron multiplier (CFX), designed and constructed by Intelcom Rad Tech Corporation of San Diego, California, is a subcritical assembly capable of continuous, stable operation and has provided us with the ability to determine more than 35 elements as major and minor components. The CFX produces a thermal neutron flux of ∼2×10³ n/cm²-sec by a 100-fold multiplication of the neutrons emitted from a 1 mg²⁵²Cf source. Of particular importance in its application at Kodak has been the determination of the halogens Cl, Br, and I, both singly and simultaneously, in various matrices including photographic materials.     

Determination of trace elements in some Nigerian vegetable based oils by neutron activation analysis

The concentrations of some essential micronutrient elements leadingto short-lived activation products in four Nigerian vegetable based oils (palmoil, palm kernel oil, sheabutter and groundnut oil) have been determined byneutron activation analysis using a small research reactor. One sample ofeach material was analysed and presented as an introduction for further investigations.Results indicate that the concentration range of the elements are 19.4–44.0µg/g for Al; 30.0–81.0 µg/g for Ca; 11.9–60.4 µg/gfor Cl; 1.43–5.96 µg/g for Cu; 7.3–28.1 µg/g for Mg;0.47–1.69 µg/g for Mn; 17.5–72.8 µg/g for Na and 0.04–0.07µg/g for V. The experimental procedure is suitable for routine determinationof micronutrient element in foods for control and monitoring purposes.     

Replacement substoichiometry and its application in activation analysis

A new method based on the substoichiometry principle has been developed. Instead of substoichiometric amounts of chelating agent, substoichiometric amounts of aqueous solution of a competing metal are used. Theoretical relationships have been derived for this method of substoichiometric replacement. Possibilities for its application are discussed.     

The application of near-infrared spectroscopy for the quality control analysis of rocket propellant fuel pre-mixes

The viability of near-infrared (NIR) spectroscopy as a technique for the quality control analysis of ingredient concentrations in a rocket propellant fuel liquid pre-mix was investigated. The pre-mix analyzed consisted of a polybutadiene pre-polymer, a plasticizer and two antioxidants. It was determined that NIR spectroscopy offered a fast and convenient method of verifying the percentage level of all four ingredients while requiring no sample preparation. The NIR methodology exhibited a high level of accuracy and precision. There was also a clear indication that the technique allowed monitoring of antioxidant depletion in the pre-mix on ageing.     

Quality control in the neutron activation analysis of biological markers for selenium in epidemiological investigations

Instrumental neutron activation analysis is routinely used at the MURR to quantify selenium in prospectively-collected biologic markers including blood serum and toenails. These specimens are typically collected from well-defined cohort populations participating in investigations assessing selenium intake and incidence of chronic disease endpoints. These epidemiological investigations, whether observational (case-control) or clinical (intervention), typically generate thousands of samples. The purpose of this paper is to assess, through evaluation of quality control results, if the achievable accuracy and precision in the measurement of selenium using NAA is adequate to determine a relative risk of 1.2 at high confidence in epidemiological studies.     

The application of neutron activation analysis to the determination of trace elements in pollen and sporopollenins

Neutron activation analysis has been used to assay the trace elements Co, Fe, Sc, Rb and Zn in pollen and derived sporopollenins. The method is capable of high precision and avoids the necessity for sample ashing and the introduction of reagent contamination. Rubidium was completely removed during the chemical isolation of sporopollenins and the remaining elements which survived chemical treatment were found in reduced amounts. The ratio of Sc: Fe in pollen and in several derived sporopollenins was found to be approximately constant. Results are discussed with reference to the possibilities of anomalous chemical behaviour of the elements resulting from irradiation.     

Measurement of bromide ion used as a solute-transport monitor via epithermal neutron activation analysis

In soil science (ca. 1970), bromide ion (Br⁻) in various forms (e.g., KBr, NaBr, SrBr₂) was introduced as a non-reactive stable tracer in solute transport studies normally moving freely with the flux of water without substantial chemical or physical interactions with the soil. Typically, Br⁻ is extracted from soil and quantified using either a bromide selective electrode (sensitivity is ≈10μg/ml) or by high-performance liquid chromatography (sensitivity is ≈0.010 μg/ml). Where the sensitivity is adequate, the selective conductivity method, which is simple, affordable and fast, is preferred. More recently (ca. 1990), workers have reported that 20% of Br⁻ tracers, at low groundwater pH, may be adsorbed by iron oxides and kaolinite when present in the alluvial aquifer. We investigated the use of Epithermal Neutron Activation Analysis (ENAA) as a means of measuring Br⁻ directly in soil samples without an extraction. ENAA was chosen because of its high theoretical advantage factor over aluminum (i.e. ≈20), the principal interfering soil constituent, calculated for the⁷⁹Br(n,γ)⁸⁰Br reaction compared to²⁷Al(n, γ)²⁸Al. Br⁻ was measured (sensitivity is ≈0.050 μg/g) in one gram soil samples from a 5 s irradiation (φ_epi=2.5·10¹² n·cm^-2·s^-1) using a BN capsule.     

An application of activation analysis of aluminum in biological materials

The behavior of aluminum compounds in animals was made clear by using non-destructive neutron activation analysis instead of radiotracer method. Basic aluminum sucrose sulfate (BASS) and dried aluminum hydroxide gel (DAHG) were orally administered to rats. The residual BASS and DAHG on gastric walls of rats were determined by neutron activation analysis. It was obtained the following results that BASS was found at the longer time in the stomach. For reason, it is seemed that BASS is hydrolyzed in gastric juice. And it could not find the aluminum in liver, kidney and spleen.     

A new internal reference method for activation analysis and its application

A new internal reference method for activation analysis has been developed. The method can be used effectively for special samples in which suitable elements as internal standards are absent and the self-shielding effect can be neglected. In this method, W_b g of element B as an internal reference is added to the sample which contains W_a g of element A to be determined, whereas the comparative standard is prepared by mixing only the element A and B in a known concentration ratio of W _a ^* /W_b. When the sample and comparative standard are irradiated by particles with the same energy distribution, even though both are irradiated separately by particles with different flux, W_a can be determined easily by the following equation. $$W_a = \left( {{{A_R } \mathord{\left/ {\vphantom {{A_R } {A_R^* }}} \right. \kern-\nulldelimiterspace} {A_R^* }}} \right)W_a^* $$ where A_g and A_R are count ratios between gamma-rays emitted by two radioactive nuclides produced from elements A and B in the sample and comparative standard, respectively. The usefulness of the present method was examined through the determination of Ti, Cr, Ni and Zr in several commercial aluminium alloys by means of photon activation, and the accuracy and precision of the method were verified.