3D SWCNTs-coumarin hybrid material for ultra-sensitive determination of quercetin antioxidant capacity

The novel 7-propinyloxy-3-(p-propinyloxyphenyl) coumarin having terminal ethynyl groups was synthesized for the first time. This coumarin has been successfully bounded covalently to single walled carbon nanotubes (SWCNTs) via the azide-alkyne Huisgen cycloaddition (Click) reaction for the preparation of a 3D hybrid material. Glassy carbon electrode was modified with the 3D SWCNTs-coumarin hybrid material for the determination of quercetin antioxidant. The proposed modified electrode is nearly 10-fold more sensitive than the bare electrode by applying the differential pulse stripping voltammetry (DPSV). In addition, the parameters of DPSV measurements such as accumulation time, accumulation potential and pH were optimized as 20 s, 200 mV and pH 2 Britton-Robinson buffer solutions in 1 μM quercetin, respectively. In the optimized conditions, the linear working range from 0.25 to 3 μM was determined. The detection and quantification limits of quercetin were found to be 20 nM and 66 nM by DPSV on the modified electrode, respectively. The DPSV procedure was also applied to test different brand tea real samples and quercetin was determined by a standard addition method with the recovery between 97.00 and 103.10.