Rapid test methods for minor components analysis of hydraulic cement.Spectrophotometric determination of manganese oxide content of Portland cement and cement raw meal

摘要

A rapid,sensitive and highly selective spectrophotometric method for the determination of manganese oxide contentt of Portland cement and cement raw meal is developed.The method is based on the reaction of manganese (II)with 1,2,4 trihydroxyanthraquinone (purpurin,PURP)in 50% v/v ethanol-water solutin at pH 8.5.The solution equilibria of manganese chelates are demonstrated and characterized for delineating optiman conditions of the complexation reaction and anlaytical aspect of the Mn-PURP system.The analysis of cement materials of variable manganese content is feasible over the concentration range 1.67-8.13 #mu#g ml~(-1) Mn,the limit of derection (at the 95% confidence level)of the method is 68 ng ml~(-1) for manganese.Under optimum conditions,the use of first derivative spectrophotomety has the advantage of high sensitivity than normal spectrophotometric method and allows the determination of 0.5 #mu#g ml~(-1) of manganese.