Comparison of electrochemical and ultraviolet detection methods in high-performance liquid chromatography for the determination of phenolic compounds commonly found in beers. Part 1. Optimisation of operating parameters
The cyclic voltammetric behaviour of five benzoic acid derivatives, gallic acid, protocatechuic acid, p-hydroxybenzoic acid, vanillic acid and syringic acid, four cinnamic acid derivatives, caffeic acid, p-coumaric acid, ferulic acid and sinapic acid, and two flavanols, (+)-catechin and (–)-epicatechin, commonly found in beers has been studied at a glassy carbon electrode. This study was used to optimise the conditions for the electrochemical detection of these compounds following high-performance liquid chromatographic (HPLC) separation. The HPLC method described is a modification of a previously described method and was optimised with respect to gradient profile, mobile phase composition and mobile phase flow-rate. A comparison was made between an ultraviolet detector and the electrochemical detector operated in series. In general, the electrochemical detector offered lower limits of detection for most of the phenolic compounds studied and, in addition, was found to offer better stability for the determination of concentrations in the 0.1–10.0 p.p.m. range.