Colorimetric determination of iron in titanium alloys

There is need for an improved method for the determination of iron in titanium alloys. In this paper a colorimetric method using o-phenanthroline is proposed. The method is applicable to the range of 0.02 to 9 per cent. iron. Two modifications of a basic procedure are described. One modification, applicable to ordinary titanium alloys, is a direct method. A second modification, applicable to alloys containing large amounts of certain alloying elements, calls for a prior separation of the iron by an ether extraction. In a direct method a one gram sample is dissolved in hydrochloric acid and an aliquot of the solution taken. Hydroxylamine and ammonium tartrate are added, the pH of the solution is adjusted by the addition of sodium acetate, and o-phenanthroline added. A study was made to find the best pH and optimum amount of o-phenanthroline for the development of the color.