Abstract: Ce(III) test paper was prepared for the detection of Ce³⁺ concentration using medium-speed quantitative filter paper as the base paper, 0.5% mass fraction cetyltrimethylammonium bromide as a modifier for base paper and 0.2% mass fraction xylenol orange as the color reagent adsorbed on base paper sequentially. A standard color chart including 11 colors was made by soaking the test paper in a series of Ce³⁺ standard solution in the concentration range of 1.000?0^-5 to 1.000 mol/L. A semi-quantitative method was established for detection of Ce³⁺ concentration in the mixed solution of Ce⁴⁺/Ce³⁺. The method was used for detection of Ce³⁺ in an electrolyte or organic reaction fluid containing Ce⁴⁺, hydroquinone, p-hydroxybenzaldehyde and 1,10-dihydroxyanthraquinone in the buffer solution of hexamethylenetetramine at pH 5.0~6.0. The results show that the method has a good accuracy and those coexisting components do not interfere with the determination. The test paper has advantages of simple manufacturing, cheapness, fast detection speed and easy operation. It is applied to the rapid monitoring of Ce³⁺ concentration in the production process.

Key words: medium-speed quantitative filter paper, modified base paper, xylenol orange, Ce(III) test paper