Abstract
Determination method of titanium dioxide in the Japanese standards for Food additives, the 6th edition is a gravimeteric method. This method is tedious. When the content in commercial samples is determined by the method, its result is sometimes over the upper limit (100.5%) (Table 1.) As alternatives, a colorimetric method with hydrogrn peroxide, and a titration method with ferric ammonium sulfate after aluminum-reduction were studied. The colorimetric method was simple, but it was difficult to obtain the titanium dioxide with a high purity for preparing the standard solution. The titration method with ferric ammonium sulfate, in which an indicator (saturated potassium thiocyanate solution) or potentiometer was used, gave the contents below 100.5% in the commercial samples (Table 4.) Therefore, the titration method was easy and rapid, and was considered to be suitable for the determination titanium dioxide as food additive.
