Abstract: A pH gradient ranging from 4.7 to 6.2 was estabeished in a flow injection system by using NaAc-HAc buffer. The absorbances of the color complexes which were formed by metal ions and chromogenic reagent (XO) were measured and the data were collected by reading bsorbances which changed with time. Identities and concentrations of metal ionic species involved were confirmed by solving the data matrix with target transformation factor analysis method (TTFA). Tests tum out that the determination of synthetic samples consisting of Cu²⁺, CO²⁺ and Zn²⁺ by this method are satisfactory.