A Green, Simple, and Rapid Detection for Amaranth in Candy Samples Based on the Fluorescence Quenching of Nitrogen-Doped Graphene Quantum Dots

With the increasing of the food safety awareness, the quality control of amaranth as the common food additives was significant for human’s physical health. The objective of this study was to establish a green, simple, and rapid fluorescence sensor for amaranth quantification detection. The nitrogen-doped graphene quantum dots (NGQDs) were synthesized under a friendly environment and non-toxic material to be employed for fluorescent donor. The addition of amaranth induced the fluorescence intensity of NGQDs to be decreased which was attributed to the reaction between carboxyl group on the NGQDs surface and sulfonic group of amaranth to form the conjugated construct regardless of the hydrogen bond. Meanwhile, the operational parameters such as pH value, reaction temperature, and incubating time were optimized. Under the optimum conditions, the fluorescence intensity varied linearly with concentration in the range from 0.4 to 3.5 μg/L with the low limit of detection at 0.15 μg/L. Moreover, this proposed fluorescence sensor had good sensitivity and specificity for amaranth determination and was utilized for real candy sample detection with satisfactory recoveries. All these abovementioned indicated that this as-prepared fluorescence sensor offers a feasible and reliable method for designing simple, environment-friendly, and rapid sensors to determine amaranth based on NGQDs, which could be further used to be a tool for practical food additives detection.