A Novel Multicommuted Flow Method with Nanocolloidal Manganese(IV)-Based Chemiluminescence Detection for the Determination of the Total Polyphenol Index

An automatic flow procedure based on a multicommuted flow analysis (MCFA) for the determination of the total polyphenolic content in food samples employing chemiluminescence (CL) as a detection technique is described. The concept of applying three-way solenoid valves in flow injection analysis was chosen in order to develop an environmentally friendly system which enables minimal consumption of reagents and waste generation. The method was based on the enhancing effect of polyphenolic antioxidants on CL of Mn(IV)–formaldehyde–hexametaphosphate system. The calibration graph obtained for standard solutions of gallic acid was linear in the range 5–150 μg L−1 with a detection limit of 1.5 μg L−1. The relative standard deviation for 20 measurements was between 1.1 and 2.4 %. The sampling rate was 60 determinations per hour. The proposed method was found to be selective to polyphenol detection and was successfully applied to the determination of the total polyphenol index in 27 diverse plant-derived food samples (wine, tea, coffee, fruit and vegetable juices, herbs, spices and extracts of olive oil). A significant correlation between the total phenolic contentment determined by the MCFA-CL method and the total reducing capacity determined by Folin–Ciocalteu method and total antioxidant activity estimated by the DPPH method was observed.