5-CHLOROSALICYLIC ACID SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF TITANIUM AND SIMULTANEOUS DETERMINATION OF TITANIUM(IV) OXIDE ANDIRON(III) OXIDE CONTENT OF PORTLAND-CEMENT

A spectrophotometric study of the titanium(IV)-5-chlorosalicylic acid (CSA) reaction was carried onto ascertain the suitability of the titan ium-CSA complex formed at pH 2.5-3 for the direct spectrophotometric d etermination of titanium, The method is simple and rapid and possesses reasonable selectivity, A linear calibration graph is obtained up to a concentration of 5.8 mu g ml(-1) of titanium, The optimum range for determination (Ringbom) is between 0.53 and 4.8 mu g ml(-1). The molar absorptivity and Sandell's sensitivity are 1.9 x 10(4) l mol(-1) cm(- 1) and 1.25 x 10(-3) mu g cm(-2), respectively, at 355 nm, Application of the method to the simultaneous determination of TiO2 and Fe2O3 in Portland cement was investigated, The absorbance at 510 nm, due to the iron(III)-CSA complex, is recommended for the determination of Fe2O3 in cement, whereas the characteristic absorption of the titanium compl ex at 355 nm is corrected for iron(III) present in the sample, The ana lysis of cement materials containing different proportions of titanium and iron is feasible over the concentration ranges 1.28-4.8 mu g ml(- 1) Ti and 18.5-40.2 mu g ml(-1) Fe3+. The limits of detection (at the 95% confidence level) of the method are 12 and 36 ng ml(-1) for titani um and iron, respectively, The individual determination of titanium in cement samples can also be achieved if iron(III) present in solution is masked by the addition of 0.01 mol l(-1) ascorbic acid. The develop ed procedure was tested by analysing several samples and was found to give satisfactory results.