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  • Author or Editor: C. Cornett x
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Abstract  

The possible association of dental amalgam surface exposure, brain mercury (Hg) levels, and pathological markers of Alzheimer's disease (AD) in the brain is the subject of an on-going study in our laboratory. Two radiochemical neutron activation analysis methods and the use of instrumental neutron activation analysis (INAA) with Compton suppression spectrometry have been evaluated for improving our INAA Hg detection limit (2.8±0.6 ng/g, wet-weight basis) in human tissue. Large numbers of samples dictated the use of a purely instrumental method or rapid, simple radiochemical separations. Human brain tissues and NIST biological standards were analyzed using a precipitation of Hg2Cl2, a solvent extraction utilizing sodium diethyldithiocarbomate, conventional INAA, and INAA with Compton suppression. The radiochemical precipitation of Hg2Cl2 proved to be the most useful method for use in our study because it provided a simultaneous, quantitative determination of silver (Ag) and a Hg detection limit in brain tissue of 1.6±0.1 ng/g (wet-weight basis).

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Abstract  

Direct determination of 226Ra in complex environmental matrices (biological and uranium ore samples) by collision-cell inductively coupled plasma mass-spectrometry was investigated. Possible polyatomic interferences were studied and their effects on 226Ra measurements were determined. The instrumental conditions for optimal signal-to-noise ratio for 226Ra were found. Concentrations of 226Ra in certified reference samples were measured using both external calibration and standard addition approaches. The best precision was obtained by applying standard additions. The absolute detection limit for 226Ra was 1 fg with optimal gas flow rates for the collision cell of 7 ml.min-1 for helium and 4 ml.min-1 for hydrogen.

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