David Madigan

Determination of proanthocyanidins and catechins in beer and barley by high-performance liquid chromatography with dual-electrode electrochemical detection

A method was developed to determine the flavanols prodelphinidin B3, procyanidin B3, (+)-catechin, and (-)-epicatechin by high-performance liquid chromatography, using dual-channel electrochemical detection. This method was especially suited to the direct analysis of beer samples and to analysis of acetone extracts of barley samples, and was capable of determining proanthocyanidins and catechins at levels of 0.1-5.0 mg l-1. The use of dual-channel electrochemical detection also enabled unambiguous peak identification by measurement of collection efficiencies. This method offered improved sensitivity and selectivity compared with ultraviolet detection, and sample preparation procedures were greatly simplified. The method was applied to the comparison of stabilized and unstabilized lagers, and to the analysis of different barley varieties grown in Ireland.

Rapid determination of 4-vinyl guaiacol and ferulic acid in beers and worts by high-performance liquid chromatography

Sensitive methods for the determination of ferulic acid and 4-vinyl guaiacol in beers and worts are described. Samples were analyzed by direct-injection high-performance liquid chromatography using...

Improved method for the determination of ascorbic acid in beer by using high-performance liquid chromatography with electrochemical detection

A method for the determination of ascorbic acid in beer by using HPLC with dual electrode electrochemical detection is described. Ascorbic acid was separated by using ion suppression chromatography on a C18 column and detected by a dual-electrode system consisting of a porous graphite high efficiency electrode followed in series by a glassy carbon amperometric electrode. It was easily detectable at sub-ppm levels in beer. The use of dual electrode detection provided a constant measurement of both peak purity and electrode efficiency.