A novel microfluidic device for estimating the total phenolic/antioxidant level in honey samples using a formaldehyde/potassium permanganate chemiluminescence system†
A microfluidic device has been investigated as a tool for the estimation of the total phenolic content/antioxidant level in honey using an acidic potassium permanganate chemiluminescence (KMnO4-CL) detection system. Selected phenolic antioxidants, including quercetin, catechin, gallic acid, caffeic acid and ferulic acid, produced analytically useful chemiluminescence signals, with detection limits ranging between 2.4 nmol L−1 for gallic acid and 34.0 nmol L−1 for o-coumaric acid. The parameters that affect the chemiluminescence intensities of each antioxidant were carefully optimized, including chip geometry, volume and area of the detection chip, pH, and concentrations of reagents used and flow rates. The effect of formaldehyde and other enhancers on CL signal intensity was extensively investigated. The method was applied to honey samples. Nine different honey samples exhibited total phenolic/antioxidant levels of 41.2 to 765.4 mg kg−1 with respect to gallic acid. The Folin–Ciocalteu (FC) assay results were well correlated with the chemiluminescence results. The method was found to be selective, rapid and sensitive when used to estimate the total phenolic/antioxidant level, producing good agreement with reported results for honey samples.