A flow-injection chemiluminescence method for determination of cinchona alkaloids in pharmaceuticals and biological fluids

A new analytical method for the determination of cinchona alkaloids by flow-injection sampling and chemiluminescence (CL) detection is developed. A weak CL can be emitted by oxidation reaction of cinchona alkaloid with potassium permanganate. The conditions for CL emission were investigated and optimized. The linear range of 1.0 x 10(-7)-8.0 x 10(-5) g mL(-1) was obtained for quinine, quinidine and cinchonine. The detection limit was 3.2 x 10(-8) g mL(-1) for quinine and 3.0 x 10(-8) g mL(-1) for quinidine and cinchonine. The recoveries of the three drugs from urine and serum samples were in the range of 95.0-105% with RSDs of 1.7-2.0%. The proposed method was used for the determination of cinchona alkaloids in pharmaceuticals and biological fluids with satisfactory result. The possible CL mechanism is also discussed.