Determination of sunset yellow in soft drinks based on fluorescence quenching of carbon dots

Fluorescent carbon dots was prepared by heating N -(2-hydroxyethyl)ethylene diaminetriacetic acid in air. The carbon dots were not only highly soluble in water but also uniform in size, and possessed strong blue fluorescence and excitation wavelength-dependent emission properties with the maximum excitation and emission wavelength at 366   nm and 423   nm, respectively. Food colorant sunset yellow whose excitation and emission wavelength at 303   nm and 430   nm could selectively quench the fluorescence of carbon dots, efficient fluorescent resonance energy transfer between the carbon dots and sunset yellow is achieved. This was exploited to design a method for the determination of sunset yellow in the concentration range from 0.3 to 8.0   μmol   L −   1 , with a limit of detection (3   σ/k) of 79.6   nmol   L −   1 . Furthermore the fluorimetric detection method was established and validated for sunset yellow in soft drinks samples with satisfactory results.