Development of a new microfluidic paper-based device (μPAD) for total phenolic content determination of beverages by the fast blue BB method.

Phenolic compounds constitute a broad family of secondary metabolites synthesized by plants responsible for their color, flavor, and astringency, as well as being very important in the human diet as the main source of antioxidants. This work describes a simple and disposable microfluidic paper-based analytical device (μPAD) for the determination of total phenolic content in different beverages. The detection was based on the colorimetric reaction between the Fast Blue BB reagent and the active hydroxyl groups of the phenolic compounds in an alkaline medium. The developed μPAD enabled TPC determination for gallic acid equivalents in the range of 5-200 mg/L and catechin equivalents of 25-125 mg/L, with a detection limit below 5.5 mg/L. Tea and wine samples were analyzed with the developed μPAD and compared to the conventional spectrophotometric method, with no significant differences (p > 0.05). The device remained stable for 7 days under a vacuum atmosphere.