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  • Author or Editor: C. Weers x
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Abstract  

The separation of metals by evaporation of their halides from solutions concentrated in mixtures of sulfuric-, hydrochloric-, and hydrobromic acid in a flow of carrier-gas can be performed at temperatures well below the boiling-point. The features of the separation process can be described in terms of the gas-volume, needed to remove half of the amount of the metal. This volume is independent of the flow-rate and decreases exponentially with increasing temperature. As an example, the isolation of trivalent arsenic from hydrogen halide solutions and mixtures of sulfuric acid and hydrogen halide solutions is discussed.

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Abstract  

The application of selective evaporation in an air-flow to the determination of arsenic and bromine in neutron-activated freeze-dried biological material is reported. Bromine is evaporated as Br2 during oxidative mineralisation. After addition of 48% HBr, arsenic is removed as AsBr3. The evaporated elements are collected in 7M NaOH;82Br (T=35.3 h) and76As (T=26.4 h) are used for quantitative assay. The chemical yield is (98±2)% for arsenic, irrespective of the amount of arsenic carrier. For bromine it varies from (70±10)% for carrier-free evaporation to (98±2)% if sufficient carrier is added. This addition is not permitted if arsenic has to be determined. The limits of determination are 5 ng·g−1 and 2 ng·g−1 respectively. The precision is ≤10% for both elements. The procedure is performed in a standardised apparatus. It was applied to the analysis of standard kale, orchard leaves and animal blood. Bromine was determined instrumentally for purpose of comparison.

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Abstract  

Combined extraction of99Mo and its daughter-product99mTc enables a rapid determination of molybdenum in biological samples by neutron activation analysis. A procedure and its application to standard kale powder and standard animal blood are reported.

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