Pulse injection analysis with chemiluminescence detection:: determination of cinnamic acid using the Ru(bipy)32+-KMnO4 system

A new chemiluminescence method for the determination of cinnamic acid is described. This method is based on the chemiluminescence produced in the reaction of Ru(bipy)(3)(2+) (bipy = 2,2'-bipydyl) and cinnamic acid with KMnO4. Under optimal conditions, the linear range and detection limit of cinnamic acid are 3.0 x 10(-9)-3.0 x 10(-6) g ml(-1) and 1.2 x 10(-9) g ml(-1), respectively. The relative standard deviation is 2.2% for the determination of 1.0 x 10(-7) g ml(-1) cinnamic acid (n = 11). The proposed method allows the determination of cinnamic acid with 2-3 orders of magnitude higher sensitivity than that of other reported methods based on various analytical techniques. It is simple, sensitive and easy to operate and can be used for the determination of cinnamic acid in human urine. A discussion on the possible reaction mechanism is presented. (C)1999 Elsevier Science B.V. All rights reserved.