CdTe量子点荧光猝灭法测定赤泥中痕量镍

Cd Te量子点具有荧光强度高和稳定性好的优点,应用Cd Te量子点荧光猝灭法分析基体复杂的样品,需要有效分离对测定干扰的金属元素和高效富集待测元素。本文以巯基乙酸(TGA)作稳定剂,采用水相合成法制备了巯基乙酸修饰的Cd Te量子点,基于镍离子在p H=10.0硼砂缓冲溶液中对Cd Te量子点的荧光具有较强猝灭作用,建立了一种测定赤泥中痕量镍的荧光光度方法。荧光猝灭反应的最佳实验条件为:Cd Te量子点的浓度3.0×10-4mol/L,反应温度为室温,反应时间10 min,在此条件下镍离子浓度在2.0×10-7~7.8×10-5mol/L范围内与Cd Te量子点的相对荧光强度呈良好的线性关系;方法检出限为1.5×10-7mol/L。本方法针对Fe3+、Co2+、Cu2+等主要基体金属元素允许量低的问题,采用25%的2-羟基-4-仲辛氧基二苯甲酮肟(N530)磺化煤油萃取回收滤液中的Ni2+,镍回收率达到99%以上;赤泥中痕量镍的测定结果与催化光度法相符,加标回收率为98.3%-104.2%。

Determination of Trace Nickel in Red Mud by Fluorescence Quenching of CdTe Quantum Dots

CdTe Quantum Dots (QDs) have the advantages of high fluorescence intensity and good stability. Using CdTe QDs as fluorescence probes to analyze samples containing complex substrates, the interference of metal elements must be effectively separated, and elements whose contents are lower than detection limits must be efficiently enriched. Thioglycolic acid (TGA) modified CdTe QDs of high fluorescence were prepared in aqueous solution using thioglycolic acid as a stabilizer. A new fluorophotometric method for the determination of trace nickel in red mud was developed based on the strong quenching effect that CdTe QDs fluorescence had been quenched by nickel ion in borax buffer solution (pH was 10.0). The suitable experimental conditions were as follows: CdTe quantum dot concentration was 3.0×10^-4 mol/L, reaction temperature was room temperature, and reaction time was 10 min. The relative fluorescence intensity of CdTe QDs was proportional to the concentration of nickel ions that ranges from 2.0×10^-7 to 7.8×10^-5 mol/L, and the detection limit was 1.5×10^-7 mol/L. In order to substrate the main lower metal elements such as Fe³⁺, Co²⁺, and Cu²⁺, the nickel ion in filtrate was extracted and recovered with solvent of 25% N530-coal oil sulfonated. The recovery of the nickel was over 99%. The proposed method has been applied to the determination of trace nickel in red mud, the results were consistent with those obtained by catalytic spectrophotometry with the spiked recoveries of 98.3%-104.2%.