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  • Author or Editor: Gae Lee x
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Abstract  

A radiochemical neutron activation analysis using solvent extraction has been applied for the determination of trace impurities in high purity nickel. Because of the high activity of58Co produced by the nuclear reaction,58Ni(n,p)58Co, cobalt should be separated from the impurities. Removal of cobalt from the other trace elements in the aqueous acidic solution containing 1M thiocyanate ion (KSCN) was achieved by extraction with 1M2-benzylpyridin (BPy) in benzene. From the result of tracer experiments, cobalt was completely separated from most other elements except Fe, Mo and Zn. To determine the experimental accuracy, NIST SRM 673 nickel oxide was analyzed and the results agreed well within 10% deviation. This established radiochemical method was applied to the analysis of high purity nickel samples.

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Abstract  

The loss of trace elements during NAA of five liquid reagents, hydrofluoric acid, hydrochloric acid, nitric acid, hydrogen peroxide and deioniyed water, has been investigated using 17 radioactive tracers of46Sc,51Cr,54Mn,59Fe,60Co,645Zn,75Se,85Sr,95Zr,113Sn,124Sb,151Eu,160Yb,177Lu,182Ta,233Pa. Two kinds of container quartz and polyethylene have been used for irradiation and also for preconcentration of the reagents. The containers were cleaned before use by washing-leaching-rinsing procedure. The reagents were preconcentrated by subboiling evaporation under the infrared lamp in clean bench. The loss of trace elements has been revealed to be severer for the reagents of hydrochloric acid and nitric acid in the container of quartz than for the other cases, while that is lowest for hydrogen peroxide.

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Abstract  

Neutron activation analysis (NAA) has been studied to improve the accuracy and sensitivity of the analysis of trace and ultratrace metallic impurities in plastic materials. There are two main problems in the analysis of plastics by NAA. First the contamination during sample preparation, especially sample crushing procedure is very serious for ultratrace analysis. Another problem is the destruction of the sample capsule due to the pressure build-up by the gases formed during neutron irradiation. A simple preparation technique of the sample crushing method using liquid nitrogen and reducing the capsule pressure by a pin hole was developed to solve the above problems. Two different irradiation and seven cooling conditions were also investigated to optimize the experimental conditions. A SRM from NIST (1632b coal) has been used to investigate the accuracy of the analysis. More than thirty elements could be analyzed in the range of sub-ppb to percent. Samples analyzed in this work were polyethylene and polypropylene which were made by different manufacturing procedure, and pigments. Two kinds of plastic products used for food and drug containers were also analyzed. It was found that NAA could be a powerful technique for the analysis of metallic impurities in plastics even though their concentrations were at ultratrace levels.

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