Electrochemiluminescence determination of pipemidic acid using sulfite as energy transfer mediator.

An electrochemiluminescence (ECL) based on energy transfer from electro-generated triplet sulfur dioxide to pipemidic acid (PPA) was studied. A weak ECL from triplet sulfur dioxide (3)SO2 * was observed when sulfite was electrochemically oxidized in sulfuric acid solution on a Pt electrode. When PPA was present, the weak ECL was enhanced. The enhanced ECL was attributed to energy transfer from (3)SO2 * to PPA. Based on the enhanced ECL, a flow-injection (FIA) ECL method for the determination of PPA was proposed. The proposed method allowed the measurement of PPA over the range of 1.0x10(-7) to 2.0x10(-5)moll(-1). The detection limit was 3.9x10(-8)moll(-1), and the relative standard deviation for 1.0x10(-6)moll(-1) PPA (n=9) was 1.3%. This method was evaluated by the analysis of PPA in pharmaceutical preparations and urine samples.