It was found that calcein could absorb the chemical energy of the oxidizing reaction between potassium ferricyanide and ketotifen accompanied with chemiluminescence (CL) emission. For the first time, CL system with calcein as a CL reagent was established. Employing this CL system, a CL method to determine ketotifen was founded. The linear range of the method was 2.0×10^－8～6.0×10^－6 g•mL^－1 with a detection limit of 8×10^－9 g•mL^－1. The relative standard deviation (RSD) was 2.1% for 5.0×10⁻⁷ g•mL⁻¹ ketotifen (n＝11). Furthermore, this method was applied to the determination of ketotifen in the tablets successfully. The mechanism of the CL reaction was discussed simply.

Key words: calcein, chemiluminescence, ketotifen, potassium ferricyanide