Highly sensitive flow-injection chemiluminescence determination of pyrogallol compounds

Abstract

A highly sensitive flow-injection chemiluminescent method for the direct determination of pyrogallol compounds has been developed. Proposed method is based on the enhanced effect of pyrogallol compounds on the chemiluminescence signals of KMnO 4–H 2O 2 system in slightly alkaline medium. Three important pyrogallol compounds, pyrogallic acid, gallic acid and tannic acid, have been detected by this method, and the possible mechanism of the CL reaction is also discussed. The proposed method is simple, convenient, rapid (60 samples h −1), and sensitive, has a linear range of 8 × 10 −10 mol L −1 to 1 × 10 −5 mol L −1, for pyrogallic acid, with a detection limit of 6 × 10 −11 mol L −1, 4 × 10 −8 mol L −1 to 5 × 10 −3 mol L −1 for gallic acid with a detection limit of 9 × 10 −10 mol L −1, and 8 × 10 −8 mol L −1 to 5 × 10 −2 mol L −1 for tannic acid, with a detection limit of 2 × 10 −9 mol L −1, respectively. The relative standard deviation (RSD, n = 15) was 0.8, 1.1 and 1.3% for 5 × 10 −6 mol L −1 pyrogallic acid, gallic acid and tannic acid, respectively. The proposed method was successfully applied to the determination of pyrogallol compounds in tea and coffee samples.