ANALYSIS OF Al_2O_3 IN SOLUTIONS AND LEATHERS PART Ⅲ: SPECTROPHOTOMETRIC METHOD FOR DETERMINATION OF Al_2O_3 IN VEGETABLE-ALUMINUM TANNED LEATHERS

摘要

This paper develops a method for determining Al_2O_3 in vegetable-aluminum and aluminum tanned leathers. The method is based on the property of Al~(3+) to form a red complex compound with aluminon at pH = 5, λ = 520nm. The preparation of the sample involves: ashing the sample at 700℃, melting the ash with 1.5g Na_2B_4O_7 at 950℃ and dissolving the melt with a dilute solution of HNO_3. The proposed method is used to determine the content of Al_2O_3 in vegetable-aluminum tanned pig and lamb leathers. The results have a very good reproducibility, with relative standard deviation, Sr = 0.5-1.3%. The absence of systematic errors in the proposed procedure has been demonstrated.