A Collaborative Study On The Determination Of Hexavalent Chromium In Container Glasses

Enforcement of the Packaging Directive 62/94 has required the development of reliable reference methods for the determination of heavy metals in glass. After considering Pb, Cd and Hg, TC2 has undertaken a collaborative study for the determination of hexavalent chromium. In this recommended procedure, the glass sample is digested with a mixture of sulphuric acid ad ammonium hydrogen fluoride at room temperature, the diphenylcarbazide is added to form a violet complex which is measured with a spectrophotometer. Decomposition efficiency, matrix effect and interferences produced by foreign ions are discussed. For container glasses of common production, no alteration of the chromium valence state was highlighted due to the dissolution process.