Nitrogen and sulfur co-doped carbon dots (NS-CDs) were synthesized by one-step solvothermal method using oleic acid as the medium, ʟ-cystine and citric acid monohydrate as precursors. Based on the “on-off-on” fluorescence quenching mode, a novel method was established for determination of both Fe³⁺ and ascorbic acid. The synthesized NS-CDs can be employed as fluorescence chemical sensors for the direct determination of free iron in the aqueous phase and indirect determination of the ascorbic acid contents of vitamin C tablets with linear ranges of 0–10 μM (n = 3) and 0–30 μM (n = 3), and detection limits of 36.6 and 102.5 nM, respectively. These results demonstrate that the proposed method exhibits good selectivity and linearity.

以油酸为介质，α-胱氨酸和柠檬酸一水合物为前驱体，通过一步溶剂热法合成了氮和硫共掺杂碳点（NS-CDs）。基于“ on-off-on”荧光猝灭模式，建立了测定Fe ³⁺和抗坏血酸的新方法。合成的NS-CD可用作荧光化学传感器，用于直接测定水相中的游离铁和间接测定线性范围为0–10μM（n = 3）和0的维生素C片剂中的抗坏血酸含量。 –30μM（n = 3），检测限分别为36.6和102.5 nM。这些结果表明，提出的方法具有良好的选择性和线性。