Detection of Neotame in Milk Beverages Using Fluorescent Carbon Dots

Neotame is a widely used artificial sweetener in milk beverages. However, excessive intake may pose potential health risks, necessitating the development of reliable detection methods. In this work, carbon dots (CDs) were designed for fluorescence enhancement detection of neotame in milk beverages. The CDs were synthesized via a one-pot solvothermal reaction at 180 °C for 8 h using 2-hydroxy-3-naphthalic acid and phthalaldehyde as precursors in ethanol. The obtained CDs demonstrated excellent storage stability, maintaining their performance for over six months at 12 °C under light-proof and sealed conditions, which exhibited their cost-effectiveness and practical utility. Upon the addition of neotame to a CDs solution diluted with ethanol, a new fluorescence emission peak emerged at 515 nm. Systematic investigation revealed that the fluorescence enhancement is attributed to modification of the surface defect states of the CDs, which leads to an increased radiative transition rate. In milk beverages, the fluorescence intensity at 515 nm showed a good linear response to neotame concentrations ranging from 2 to 100 μM, with a calculated detection limit of 1.55 μM (0.58 mg/L). The proposed method exhibits high specificity and strong anti-interference capability, and its application potential in milk beverages has been verified.