摘要
以红枣为碳源,通过一步水热法合成了发光碳量子点(CQDs),通过荧光光谱、紫外-可见吸收光谱、红外光谱及X-射线粉末衍射光谱对其发光特性进行了研究,测定了其荧光寿命及量子产率.发现在pH=3.29的柠檬酸-柠檬酸钠缓冲溶液中,维生素B_(12)对该CQDs荧光具有明显的猝灭作用,提出了以红枣CQDs为荧光探针测定维生素B_(12)的新方法,CQDs的荧光猝灭强度ΔF与维生素B_(12)的浓度呈良好的线性关系,线性范围为9.0×10~(-8)~1.5×10~(-5) mol/L,相关系数为0.999 2,方法检出限为7.1×10~(-8) mol/L.该方法用于样品中维生素B_(12)含量的测定,回收率为98.5%~103.5%.通过荧光寿命、紫外吸收光谱的变化以及温度对猝灭常数的影响,确定了该CQDs与维生素B_(12)的猝灭类型为动态猝灭.
Fluorescent carbon quantum dots(CQDs)were synthesized by a one-step hydrothermal method with red dates as precursors in this paper.The luminescence properties of the CQDs were studied by fluorescence spectroscopy,UV-vis spectrum,transmission electron microscopy,infrared spectrum,and X-ray powder diffraction spectroscopy.The fluorescence lifetime and quantum yield were measured.It was found that Vitamin B_(12) has a strong quenching effect on the fluorescence of the CQDs.A new method for the determination of Vitamin B_(12) with red dates CQDs as fluorescent probe was proposed.In the citric acid-sodium citrate buffer solution with pH=3.29,the quenching values of CQDs fluorescence intensityΔF have a good linear relationship with the concentration of Vitamin B_(12) from 9.0×10~(-8) mol/L to 1.5×10~(-5) mol/L with the detection limit of 7.1×10~(-8) mol/L.The linear correlation coefficient was 0.999 2.The method has been used to determine the content of Vitamin B_(12) in the samples with satisfactory results.The dynamic quenching between the CQDs and Vitamin B_(12) was proved by the changes of fluorescence lifetime as well as the absorption spectrum and the effect of temperature on the quenching constant.
引文
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