Carbon dot and silver nanoparticle–based fluorescent probe for the determination of sulfite and bisulfite via inner-filter effect and competitive redox reactions.

A new sensitive fluorescent probe (CDs-AgNP/H2O2) for detecting sulfite and bisulfite (SO32− and HSO3−) based on the inner-filter effect (IFE) between silver nanoparticles (AgNPs) and carbon dots (CDs) was developed. Because of the spectral overlap between the absorption of AgNPs and the excitation of CDs, the fluorescence of CDs can be quenched by AgNPs owing to the IFE. H2O2 weakens the IFE and restores the fluorescence due to the oxidation of AgNPs by H2O2. However, the existence of SO32−/HSO3− can quench the fluorescence again as a result of redox reaction between SO32−/HSO3− and H2O2. The results showed a broad linear range of 20–200 μM with a low limit of detection (3.02 μM) toward SO32−/HSO3−. The combination of IFE and redox reaction led to improvement of the sensitivity and selectivity. The probe was implemented to measure SO32−/HSO3− in various agricultural products and foods with acceptable results (80.6 to 118.9% recovery). [ABSTRACT FROM AUTHOR]