Determination of Germanium in Boiler Ash by Gasification Separation-Atomic Fluorescence Spectrometry

In order to improve the use value of boiler ash, a method of gasification separation-atomic fluorescence spectrometry was established for determination of the content of germanium in boiler ash. A mixed acid composed of sulfuric acid, hydrochloric acid, hydrofluoric with volume of 2, 15, 10 mL was used to digest boiler ash samples under the condition of magnetic stirring and heating at 120℃. 50% (volume fraction) phosphoric acid solution was adopted as absorbent for collection of the distilled gaseous germanium halide (GeCl₄ and GeF₄). The obtained sample solution was analyzed by atomic fluorescence spectrometer with 30 g·L^-1 potassium borohydride solution containing 5 g·L^-1 sodium hydroxide as reducing agent and 3% (volume fraction) phosphoric acid solution as carrier. As found by results that linear relationship between mass concentration of germanium and its respective fluorescence intensity was kept in the range of 0.1-60 μg·L^-1, with detection limit (3s/k) of 0.285 μg·kg^-1. The spiked recovery test was made on 3 boiler ash samples, giving values of recovery in the range of 91.2%-106%, and RSDs (n=7) were ranged from 3.0% to 4.5%.