Quantum dots and fluorescence compounds for biogenic amine sensing

Abstract

A sequential injection analysis (SIA) with chemiluminescence (CL) detection system was developed for determination of total antioxidant content (TAC) in wines and beverages. The method is based on the CL reaction between luminol and hydrogen peroxide in alkaline conditions with the presence of a K3Fe(CN)6 catalyst. Antioxidants in the sample scavenged a reactive oxygen species as hydrogen peroxide and the decrease in CL intensity was observed that related to the TAC in sample. A cost-effective CL detection system with a home-made spiral configuration flow-cell was designed and constructed by inexpensive materials. The spiral chemiluminescence flow-cell was made from an opaque white polymer of polymethyl methacrylate (PMMA) or acrylic plastic. Furthermore, a light-to-voltage optical sensor was used as a low-cost alternative detector which is small and was also used for the miniaturization of instrument. Thus, the developed CL detection system is cost-effective, portable and has the ability to connect with flow-based systems. The optimum conditions of SIA-CL method were studied and the linear range for gallic acid was obtained ranging from 0.5 to 5.0 mmol L-1, the limit of detection (LOD) was 0.25 mmol L-1 and the limit of quantitation (LOQ) was 0.84 mmol L-1. The reproducibility of the method was investigated and the between day %relative standard deviation was in the range of 2.2 to 5.4%. The %recovery was between 95.8 and 105.6% and the sample throughput was 60 samples h-1. The proposed method was successfully applied for the determination of TAC in wine and beverage samples and the results were not significantly different when compare with the reference method. Therefore, the developed SIA-CL method is simple, fast, accurate and consume less reagent.