Rapid determination of germanium in coal, soil and rock

Abstract

Cluley's colorimetric method for the determination of germanium in coal with phenylfluorone is modified to speed up the rate at which coal samples can be analyzed. The method is also adapted to the determination of germanium in soils and rocks. To avoid the time-consuming step of neutralizing after the alkaline fusion, as described by Cluley, coal samples are ashed at 550° C. Soils and rocks are decomposed with hydrofluoric acid and the residue is fused with a mixed flux of potassium bisulfate and persulfate. The germanium in the coal ash or in the fusion product is then dissolved in 1+1 hydrochloric acid and distilled on a specially designed distillation rack, on which six samples can be distilled at once. Although the maximum absorbance of the germanium phenylfluorone complex was found to be between 500 and 505 m/* (millimicrons), the absorption is measured at 510 m,u to minimize interference by reagent. However, visual comparison with standards is preferred to the instrumental method of estimation. A sensitivity of 2 ppm (parts per million) germanium in the coal and 1 ppm in soils or rocks is obtained. About 50 coal samples can be analyzed per man-day.