Efficiency improvement for sulfated ash determination by usage of a microwave muffle furnace.

The usefulness of microwave muffle furnaces for increasing the efficiency of sulfated ash determination through automation was investigated. Substances critical in their behavior were selected as model substances for this purpose: megestrol acetate and a phthalazine derivative as substances with high foaming indices and azelaic acid as a substance with a high spatter index. The selection of an optimal temperature sequence in conjunction with quartz crucibles and/or with a spatter guard made of quartz filter paper made it possible to handle even these critical substances. The analysis results were comparable and reproducible in terms of classical pharmacopeia methodology.