Validation of a micro-assay based on the pH differential method to quantify total monomeric anthocyanins in red cabbage (Brassica oleracea var. capitata f rubra)

Anthocyanins are water-soluble flavonoids, in nature found in flowers, fruits and some vegetables such as red radish, red cabbage and red onion. Due to its characteristics as a natural colorant and its bioactive properties, the food, pharmaceutical and cosmetic industries have focused their interest on them. To quantify these compounds, some spectrophotometric and chromatographic techniques exist, its use, however, is in disadvantage because of the long execution times and high cost of the reagents. Therefore, the aim of the present work was to evaluate the validation parameters of a spectrophotometric microassay based on the pH differential method to quantify the total monomeric anthocyanins content of red cabbage. The validation of the method by microassay was carried out evaluating the selectivity, specificity, linearity, limits of detection and quantification, precision, robustness and applicability. The results of selectivity and specificity showed that only total monomeric anthocyanins can be identified with the validated method. Which proved to be linear (r 2 = 0.9999), precise (RSD