Photometric Determination of SiO2 and Fe₂O₃ in Gypsum with Microwave Assisted Sample Digestion

In the photometric determination of SiO2 (by molybdenum blue method) and Fe2O3 (by o-phenanthroline method) in gypsum,modified microwave assisted sample digestion was adopted in the dissolution of gypsum sample in NaOH solution. Under the optimized conditions,including working parameters of the microwave oven and concentration of the NaOH solution,the dissolution of gypsum sample was completed in 180 s. Results of determination of SiO2 and Fe2O3 in 3 gypsum CRM′s by the present method were found in conformity with the certified values. No significant difference was observed between the values of SiO2 and Fe2O3 found by the microwave assisted sample digestion method and by the conventional alkali fusion method.