在规定的条件下和pH 11的碱性溶液中,通过镉(Ⅱ)、巯基乙酸(TGA)与硒化氢钾乙醇溶液之间的反应制得TGA修饰的CdSe量子点(QD′s),再将此量子点和硫化钠溶液反应制得TGA修饰的CdSe/CdS量子点。基于喹诺酮类抗生素司帕沙星与CdSe/CdS量子点的荧光猝灭作用,用CdSe/CdS量子点作为荧光探针测定了样品中微量司帕沙星含量。用荧光光谱、紫外光谱研究了CdSe/CdS量子点与司帕沙星的相互作用。试验发现,pH为6.47的磷酸盐缓冲溶液中,量子点的浓度为2.5×10-4mol·L-1时,司帕沙星的质量浓度在0.5~30 mg·L-1范围内与CdSe/CdS量子点荧光猝灭强度呈线性关系,方法的检出限(3s/k)为0.14 mg·L-1。方法应用于司帕沙星片剂司帕沙星含量的测定,分析结果与标示量一致;用于牛奶中司帕沙星残留量的检测,并用标准加入法做回收试验,测得回收率在95.3%~106.8%之间。

Through reaction of Cd(Ⅱ), thioglycollic acid (TGA) and alcoholic solution of potassium selenium hydride in an alkaline solution of pH 11, TGA modified CdSe quantum dots were prepared, which were further reacted with Na2S solution to give TGA modified CdSe/CdS quantum dots (QD′s). Based on the fluorescence quenching action of the antibiotic sparfloxacin (SPFX) on the QD′s, the CdSe/CdS QD′s were used as fluorescence probe for determination of SPFX, and principle of this fluorescence quenching reaction was studied by fluorescence spectrometry and UV-spectrometry. It was found that in a PBS of pH 6.47 and keeping the concentration of CdSe/CdS QD′s at 2.5×10-4mol·L-1, linear relationship between the magnitude of fluorescence quenching and mass concentration of SPFX was kept in the range of 0.5-30 mg·L-1, with detection limit (3s/k) of 0.14 mg·L-1. In the analysis of SPFX tablets by the present method, values of SPFX contents found were in consistency with the labelled value. SPFX was also determined in milk samples by this method, and using milk sample as matrix, recovery of the method was tested by standard addition method, values of recovery found were in the range of 95.3%-106.8%.