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  • Author or Editor: K. Abbass x
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Abstract  

Resonance neutron activation and gamma-ray spectrometry were used to determine traces of iodine in biological materials. The method developed is purely instrumental and fairly rapid. The major interfering activities of24Na,38Cl,36Mn and82Br were significantly reduced by irradiating the samples inside a shield of Cd, NaCl, MnBr2 and MnO2. Neutrons with energies close to the resonances of Na, Cl, Mn and Br were absorbed in the shield and did not activate the sample while neutrons with energies close to the resonances of iodine were not absorbed appreciably. Thus the activity of128I was enhanced relative to the interfering activities. The 442 keV gamma of128I (T=25 min) was measured using a high-resolution Ge(Li) detector and a multichannel analyzer. Sensitivity of 0.05 ppm was obtained.

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Abstract  

A comparative study is made on different activation methods for mercury analysis. Mercury concentrations down to 0.1 ppm were determined instrumentally via the isotopes197Hg (T=65 h) and203Hg (T=47 d). A high-resolution Ge(Li) detector was used in measuring the activity and a small computer for data reduction. Up to 500 samples were measured daily. Chemical separations were performed on samples with low mercury concentrations. Sensitivity of 0.01 ppm was attained by precipitating HgS from basic solutions and counting197Hg on NaI(T1) detector. A new rapid instrumental method was also developed based on199mHg (T=43 min). This short-lived isotope was activated with resonance neutrons. The sensitivity of the method is 0.5 μg and it requires only 1 hr.

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