Ascorbic acid (AA) was detected by using a nano-switch of ferric ions (Fe3 +),the nitrogen-doped fluorescence carbon nanodots (N-FCDs) was synthesized by one-step hydrothermal carbonization of chitosan at a mild temperature.The as-obtained N-FCDs exhibited good water dispersibility,excellent pH stability,and strong fluorescence.The results showed that the fluorescence of the N-FCDs could be effectively quenched by Fe3 + and then be sensitively turned on in the presence of AA via an "off-on" fluorescence response through the oxidation-reduction between Fe3+ and AA.A wide detection linear range for AA was found to be from 1 μmol/L to 200 μmol/L with a detection limit of 0.06 μmol/L.The switch sensor was also successfully applied to detect vitamin C tablets with satisfactory recovery ranging from 96.9％ to 106％,exhibited great opportunities for practical application in food and clinical system.%以壳聚糖为前驱体,在较低温度下通过水热法一步合成了掺氮碳量子点(N-FCDs),合成得到的N-FCDs具有良好的水溶性、pH稳定性及优良的荧光特性.实验表明:Fe3+能猝灭N-FCDs溶液的荧光,灵敏度高且选择性好;当还原性的抗坏血酸加入荧光猝灭的Fe3+-N-FCDs体系后,体系猝灭的荧光因Fe3+的还原反应又得以恢复.由此,可实现对抗坏血酸的灵敏检测,检测的线性范围为1～200 μmol/L,检出限为0.06 μmol/L.此外,Fe3+-N-FCDs的抗干扰能力强,可实现维生素C药片中抗坏血酸含量的检测,检测结果令人满意.
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