HPLC method for the quantification of procyanidins in cocoa and chocolate samples and correlation to total antioxidant capacity

Monomeric and oligomeric procyanidins present in cocoa liquors and chocolat es were separated and quantified in four different laboratories using a nor mal-phase high-performance liquid chromatography (HPLC) method with fluores cence detection. Procyanidin standards through decamers were obtained by ex traction from cocoa beans, enrichment by Sephadex LH-20 gel permeation chro matography, and final purification by preparative normal-phase HPLC. The pu rity of each oligomeric fraction was assessed using HPLC coupled to mass sp ectrometry. A composite standard was then prepared, and calibration curves were generated for each oligomeric class using a quadratic fit of area sum versus concentration. Results obtained by each of the laboratories were in close agreement, which suggests this method is reliable and reproducible fo r quantification of procyanidins. Furthermore, the procyanidin content of t he samples was correlated to the antioxidant capacity measured using the OR AC assay as an indicator for potential biological activity.