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Abstract  

A method of rapid determination for indium, nickel and copper in Spinach (NBS; SRM-1570) by substoichiometric radioactivation analysis is described. The method is based on the principle that an equal amount of non-irradiated test sample is added to the irradiated standard sample and subsequent substoichiometric extraction for the irradiated test and standard samples is carried out. Indium is extracted as diethyldithiocarbamate into carbon tetrachloride, nickel as dimethylglyoximate into chloroform and copper as dithizonate into carbon tetrachloride. The radioactivities of these extracts are measured by NaI(Tl) or Ge(Li) detector coupled with pulse-height analyser. The analytical results obtained by the method were in good agreement with our published values and certified values by NBS.

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Abstract  

The described method is suitable for the determination of about 20 trace-elements by neutron activation analysis and radiochemical group separation with one standard (flux-monitor) instead of the simultaneous irradiation of the elements investigated. The activity of the flux-monitor delivers the correction-factor, under the same irradiation conditions (neutron spectrum), between the irradiation of a complete standard-set and the different irradiations of unknown samples. The FRN (Research Reactor Neuherberg) is not working continuously so that it is necessary to add different irradiation times of some hours to our routine irradiation time of 24 hours. The correction factors for these complicated working conditions in neutron activation analysis are mathematically described and discussed.

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Abstract  

The pure-element sample weights for standards of 70 elements, including their 194 principal (n, ) products, have been calculated by the APCP, each for the optimum condition set for the analysis by INAA of multi-element samples of all kinds of matrix materials. From these APCP results, pure-element LODs have also been calculated for these same conditions, and compared with the 1980 Guinn/Hoste table of LODs.

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Abstract  

A technique for using internal standards in the determination of Si in rocks using fast neutron activation is presented. Different weights of barium acetate were irradiated for 30 seconds then cooled for 10 seconds before counting for one minute. A peak area, at 0.662 MeV due to137mBa, versus weight of barium calibration curve (I) was made. Similarly, barium acetate, which served as the neutron flux monitor, was mixed with known weights of standard rocks, BCR-1 and G-2. Then a peak area (at 1.78 MeV due to28Al) versus weight of silicon (present in the standard rocks) calibration curve (II) was constructed which was corrected for flux variations. Flux corrections were made possible using curve (I). Utilizing curve (I) and curve (II) the percentage Si in granite samples obtained from Llano, Texas, was determined. This technique avoids any external neutron monitor or sample rotation system. The applicability of this approach may be limited to samples in which the internal flux monitor can be dispersed.

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To the Editor, In a recent article appearing in this Journal, Han et al. [ 1 ] reported the specific heat capacity and standard molar combustion of taurine. There are several errors in the paper, and the quality of the measured

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Abstract  

EPR-spectroscopic properties (line-intensity,-width, andg-factors) of pyrolized at 550°C sucrose, MgO and MgO doped with Mn2+ ions (500∶1) remain unchanged after high-dose (1–100 kGy) irradiation, whereas CaO gives an EPR signal. These properties of these materials make it possible to use them as internal reference EPR standards in the work under conditions of strong ionisation environment, for precise determination of theG-values of other materials, for obtaining exact magnitudes of increase of the EPR response when the method of additional dose is applied, to follow the kinetics of decay of some radiation induced defects.

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Abstract  

Chromium is recognized to be an essential trace element in several biological systems. It exists in many biological materials in a variety of chemical forms and very low concentration levels which cause problems for many analytical techniques. Both instrumental and destructive neutron activation analysis were used to determine the chromium concentration in Orchard Leaves, SRM 1571, Brewers Yeast, SRM 1569, and Bovine Liver, SRM 1577. Some of the problems inherent with determining chromium in certain biological matrices and the data obtained here at the National Bureau of Standards using this technique are dicussed.

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Abstract  

New synthetic standard samples (SSB-1 and SSB-2), produced on the basis of phenol-formaldehyde resin in the shape of tablets are suggested. The samples are intended for INAA of biological materials. SSB-1 and SSB-2 samples contain Se, Cr, Au, Sb, Ag, Rb, Fe, Zn, Co and Ca, Ba, Hg, Sn, Br, Cs, Ni, Sc and Na. The concentrations of these elements are chosen so that the maximum statistical error of -quantum registration by the semiconductor detector should not exceed 3% when irradiating samples in a neutron flux of 1013 n·cm–2·s–1.

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Abstract  

Fifteen elements at trace levels have been determined by neutron activation analysis in the biological standard kale distributed byBowen. La, Br, As, Se, Sc, Ag, Zn, Co, Cr, Sb, Eu, Fe, and Zr have been determined by a nondestructive technique using a high-resolution Ge(Li) detector. Two more elements, Au and Hg, have been determined after radiochemical separation. The nondestructive procedure is shown to yield data in generally good agreement with those obtained by destructive techniques. Potential sources of error in the nondestructive technique are discussed.

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Abstract  

Instrumental neutron activation analysis (INAA), and inductively coupled plasma mass spectroscopy (ICP-MS) were applied to the determination of major elements and rare earth elements in Japanese Standard Soil Materials (NDG-1 to -8). Eight major elements, Al, Fe, Ti, Ca, Mg, Mn, K, and Na were determined by INAA. A comparison of the data for rare earth elements obtained by INAA and ICP-MS shows that the data of the contents determined by the two different analytical methods are in fairly good agreement with each other.

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