Determination of metanil yellow dye in turmeric powder using a unique fluorescence Europium doped carbon dots

Determination of Metanil yellow dye using fluorescent Europium doped Carbon dots. • Photoluminescent Eu doped Carbon dots were synthetized from Tannic acid and Eu(III) • The synthetized Eu-C-dots were characterized by UV, SEM, TEM, and FTIR techniques. • Eu-C-dots were utilized as fluorometric reagent for determining metanil yellow. • The method has been applied for determining metanil yellow in curcumin powder. Turmeric, a spice known for its therapeutic benefits, is a major source of curcumin which is a polyphenol with anti-inflammatory properties. It aids in treating arthritis, anxiety, metabolic syndrome, liver disease, hyperlipidemia, oxidative and inflammatory diseases. In this study, a novel fluorescence probe was designed to detect the adulteration of curcumin by metanil yellow (a harmful artificial dye). The probe was synthesized from the carbonization and conversion of the Tannic acid-Eu 3+ complex to bright fluorescence Eu-carbon dots in the presence of orthophosphoric acid. The size, morphological, and optical features of the formed Eu-carbon dots were characterized by UV, SEM, TEM, and FTIR techniques. Furthermore, the formed Eu-carbon dots possess unique fluorescence excitation and emission features at 307.5 nm and 340.6 nm, respectively. These fluorescence features can be successfully quenched upon the addition of metanil yellow dye. The value of quenching in the fluorescence intensity of the Eu-C-dots was directly proportional to the dye's concentration. The LOD value for the proposed method was 0.390 µg/mL with a linear range of 1.0-15.0 µg/mL. Furthermore, the methodology exhibited good recovery values for determining the studied dye without any interference from the presence of curcumin.