Polarographic determination of aluminum in titanium alloys

Considerable interest has been shown in titanium metal because of its combination of desirable properties, including its favorable strength to weight ratio and its resistance to corrosion. Since titanium-aluminum alloys are fairly common, there is need for an accurate method of determining aluminum over a wide range of concentrations. This paper describes an accurate and fairly rapid polarographic method for determining aluminum based on the reduction of an aluminum-azo dye complex after removing titanium, and other interferences by cupferron precipitation, followed by electrolysis at a mercury cathode when necessary. The reduction takes place at — 0.44 volt versus the saturated calomel electrode in a solution buffered at pH 4.6 with acetate. The method is sensitive from 0.01 mg to 0.50 mg of aluminum per 50 ml, covering a range of 0.005 to 10.0 per cent aluminum.