Sequential determination of titratable acidity and tartaric acid in wines by flow injection spectrophotometry

摘要

A flow injection manifold is proposed for the sequentialdetermination of titratable (total) acidity based on apseudotitration and of tartaric acid based on theformation of a coloured vanadate complex. The methodinvolves in-line dialysis prior to injection to avoidinterference from the sample background absorption inthe spectrophotometric detection. The changes in thecolour of both reactions were monitored using two flowcells aligned in the optical path of a singlespectrophotometer. Wine samples were analysed withoutany sample pre-treatment; table wines in the range 1–10g l21 (total acidity) and 0.5–4 g l21 (tartaric acid) andport wines in the range 1–8 g l21 (total acidity) and 0.5–5g l21 (tartaric acid). Sixteen samples can be measured perhour, and the results were comparable to those obtainedby reference procedures for both determinations. RSDs(n = 10) generally lower than 3% were obtained