Composable paper-based analytical devices for determination of flavonoids

Abstract A concept of composable paper-based analytical devices (composable μPADs) is proposed. The key idea of composable μPADs is to develop a paper-based analytical platform that can be easily and quickly assembled into a desired architecture from standard pre-made paper-based parts. Here it is illustrated by the determination of several flavonoids, as an important class of natural polyphenol antioxidants. Two methods for the determination of flavonoids, at high (a two-part configuration) and at low (a three-part configuration including an additional preconcentration zone) concentrations, were developed. The principle for flavonoid detection was based on their ability to reduce silver nitrate to silver nanoparticles (AgNPs) producing an intense surface plasmon resonance band. The effects of main factors on the formation of AgNPs and the analytical response in proposed μPADs were studied. The concentration limits of detection were 2.3, 5.2, 14 μg mL-1 and the absolute limits of detection were 0.12, 0.26, 0.70 μg for quercetin, morin and dihydroquercetin, respectively. To determine flavonoids at low concentration level, a three-part configuration of a composable μPAD utilizing preconcentration on magnetic hypercrosslinked polystyrene was used. It was shown that such preconcentration increases 5 times sensitivity of morin determination. The method was applied to the analysis of hawthorn tincture and onion peel.