Integrated instrumental setup comprising an automatic solution handling module and homemade luminometer with two photodetectors for the determination of antioxidants in wines

Abstract

This study describes the development of an integrated instrumental setup, comprising a multi-commuted flow analysis module for solution handling and a homemade luminometer assembled with two photodetectors for luminescence detection. This setup controlled by an Arduino Due board was used to develop an analytical procedure for determining antioxidants in red and white wines, using chemiluminescence detection. The analytical procedure is based on the reaction of hypochlorite with antioxidants present in wine, followed of oxidizing reaction with luminol in an alkaline medium (pH > 9). After determining the optimal operational parameters, the following analytical parameters were obtained: linear responses for gallic acid concentrations ranging from 0.75 to 4.0 g L⁻¹ (r² = 0.999) for red wine and from 75 to 500 mg L⁻¹ (r² = 0.994) for white wine, a coefficient of variation of 2.71% (n = 9) for a wine sample with an antioxidant concentration of 1.57 g L⁻¹ in gallic acid equivalent, recoveries ranging from 85 to 114%, an analytical throughput of 100 determinations per hour, consumption of 0.35 μg of hypochlorite and 53 mg of luminol per determination, and limits of detection of 0.25 g L⁻¹ and 29 mg L⁻¹ for red and white wine, respectively.