Flow injection analysis of pyrogallol with enhanced electrochemiluminescent detection

Potential dependent inhibition and enhancement effects of pyrogallol on the electrochemiluminescence of luminol in alkaline solutions were found. On t he basis of enhancement effect, a flow injection method was developed for t he determination of pyrogallol. The method was simple, rapid and sensitive with a detection limit of 1.6 x 10(-8) mol/l, linear range of 7.0 x 10(-8)- 1.0 x 10(-4) mol/l, relative standard deviation of 2.2% for eleven measurem ents of 5.0 x 10(-6) mol/l pyrogallol. This method was successfully applied to determine the content of pyrogallol in a pyrolysis mixture of gallic ac id. The mechanism of the inhibition and enhancement was proposed. Pyrogallo l mostly reacted with the di-oxygen species electrogenerated at potentials more positive than 0.50V versus Ag/AgCl and generate superoxide radicals ad sorbed on the electrode surface, which led to the enhancement of the electr ochemiluminescence of luminol. (C) 2000 Elsevier Science B.V. All rights re served.