Chemiluminescence of nitrogen-rich quantum dots in diperiodatoargentate(III) solution and its application in ferulic acid analysis

A novel chemiluminescence (CL) system based on the reaction of fluorescent water-soluble nitrogen-rich quantum dots (N-dots) and diperiodatoargentate(III) (DPA) was developed. The prepared N-dots have a small size (≤10 nm) and high percentage of nitrogen (39.9 %), which exceeds the content of carbon in the same N-dots. The N-dots exhibit characteristic blue fluorescence under UV light and up-conversion luminescence. The relatively intense CL emission is based on the direct oxidation of N-dots by DPA. The CL emission may be attributed to the high nitrogen content and the special structure of the N-dots. The CL mechanism of N-dots and DPA was investigated by using CL, UV-Vis absorption, IR, fluorescence, and radical scavenging experiments. This investigation provides a way to study the optical properties of N-dots. The analytical applicability of the N-dots and DPA CL system in the determination of ferulic acid (FA) was explored. The CL intensity was linearly proportional to the concentration of ferulic acid from 3.0 × 10^-7 to 1.0 × 10^-5 g mL^-1 with a detection limit of 8.0 × 10^-8 g mL^-1 (3σ); the relative standard deviation was 2.4 % for 4.0 × 10^-7 g mL^-1 FA (n = 9). The proposed method was successfully applied to the determination of ferulic acid in Angelica sinensis. The study provides valuable insight into the role of nitrogen-rich quantum dots in CL.