Antimony atomic absorption spectrometer

Using sodium borohydride, arsenic ions are reduced to arsenic hydride, transferred to a heated quartz cuvette with the aid of a current of inert gas, decomposed thermally, and the absorption of the atoms is measured in the beam of an atomic-absorption spectrometer. In the hydride technique, the element which is to be determined is volatilized as a gaseous hydride and separated off from the matrix. Interferences may occur if there is a considerable excess of elements such as antimony, tin, bismuth, mercury, selenium or tellurium, which may also be volatilized using this technique. 

The quality characteristics for an inhomogeneous sample can be improved by complexing with ethylenediamine-iV,V,iV, iV -tetraacetate (EOTA) after reaction. The antimony compound is converted to stibine with sodium borohydride. The volatile metallic hydride is transferred with helium to a heated quartz cuvette at the beam entrance of an atomic absorption spectrometer. There the hydride is thermally decomposed at 900°C and the antimony is determined by AAS. Calibration is carried out by the addition of standards. 

The instruments needed for the determination of antimony comprise an atomic absorption spectrometer with electrodeless Sb discharge lamp and potentiometric recorder, a hydride system with quartz cuvette and polypropylene reaction vessel, a pressure decomposition system with a temperature-controlled heating block, and an evaporation apparatus together with various adjustable micropipettes. 

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