Extraction spectrophotometric method for determination of aluminium in silicates

A simple, rapid and sensitive method has been worked out for spectrophotometric determination of macro and micro amounts of alumina in ceramic raw materials and finished products, including glasses. The method is based on the extraction of aluminum oxinate into chloroform after masking of titanium with chromotropic acid and of iron with ascorbic acid and 1,10-phenanthroline or ferrocyanide at pH 5.2. The absorbance is measured at 385 nm. Interference by Cu, Zn, Cd, Ni and Co, when present, is overcome by stripping them as cyanide complexes by shaking the chloroform extract with potassium cyanide solution. Zr is masked with quinalizarin sulphonic acid and fluoride with BeSO(4).