【摘要】 目的建立一种快速测定大米中镉的方法。方法用硒粉、氧化镉、石蜡、油酸以及硫单质在有机相中合成核壳结构的CdSe/CdS,加入巯基乙酸使得油溶性的CdSe/CdS转移成水溶性的CdSe/CdS量子点。牛血清蛋白(BSA)经NaBH4还原成dBSA,然后将dBSA修饰在CdSe/CdS表面,形成dBSA-QDs。而dBSA-QDs在待测的Cd2+作用下发生荧光增强,且荧光增强程度与Cd2+的浓度之间符合Langmuir公式。实验考察了pH、温度、C dBSA/C QDs摩尔比以及高浓度的Ag+、Cu2+、Al3+、Cl-、F-、NO3-、FeF63-、Mg2+、Ca2+、Zn2+干扰离子对测定结果的影响。同时还研究了dBSA-QDs检测Cd2+的机理。结果在最优化实验条件下,方法的检出限达到8.3μg/kg,标准偏差为2.7%。将该方法用于实际大米样品的检测,与原子吸收光谱法测定结果相比,两种方法具有良好的一致性。结论该方法简单、快速且廉价,可以用大米中镉的检测。更多还原

【Abstract】 Objective To develop a new method for rapid determination of cadmium in rice samples. Methods The core-shell CdSe / CdS QDs were synthesized by using selenium powders,cadmium oxide powders,liquid paraffin,oleic acid and sulfur power. The synthesized oil- soluble CdSe / CdS QDs was transferred into water- soluble QDs by adding mercaptoacetic acid. The dBSA was obtained by chemical reaction of BSA and NaBH 4. Then dBSA was coupled to CdSe / CdS core- shell QDs to form the dBSA- QDs bioconjugates. It was found that the enhanced luminescence intensity of the dBSA- coated QDs bioconjugates in a concentration of Cd2 +dependence is best described by a Langmuir binding isotherm equation. The effect of the pH, temperature,CdBSA / CQDs molar ratio and the interference of Ag+,Cu2 +,Al3 +,Cl-,F-,NO 3-,FeF 6 3-,Mg2 +,Ca2 +, Zn2 +on the fluorescence intensity of dBSA- QDs bioconjugates was investigated in the present study. In addition,the mechanism of Cd2 +detection by dBSA- QDs was also studied. Results Under the optimized conditions,the dBSA- QDs bioconjugates were used to detect Cd2 +with a detection limit of 8. 3 μg / kg and a relative standard deviation of 2. 7%. It can be used for direct analysis of rice samples,and the results were very close to those detected by AAS. Conclusion The method is simple, rapid and low- cost,it can be used to detect cadmium in rice samples.更多还原