Flow injection determination of total catechins and procyanidins in white and red wines

Abstract

An easily automatable flow-injection (FI) method for the determination of total catechins is reported. The method is based on the reaction of vanillin in acid medium to yield a coloured product with maximum absorption at 500 nm. After optimisation by the univariate and multivariate approaches as required, the linear range was established (between 10 and 90 mgL-1 and 10 and 250 mgL-1 for white and red wines, respectively). Then, the assessment of the proposed versus the reference method was studied in terms of repeatability (2.57 mgL-1), reproducibility (3.56 mgL-1) (no significant differences were found), detection and quantification limits (not far from those of the reference method and always sufficient for the determination of catechins in any type of wine), traceability (excellent correlation under all conditions) and sample throughput (23 samples h-1 for the proposed method versus 3 samples h-1 for the reference method)