碳点荧光猝灭法测定粉煤灰中痕量钴

在pH 6.80的B-R缓冲溶液中,基于钴离子对水溶性碳点(CDs)的荧光具有显著的猝灭作用,建立了一种测定钴离子的荧光光度法。在5 mL比色管中,依次加入0.5 mL 3.6×10^-4 mol/L荧光碳点溶液(以碳计)、1.0 mL pH 6.80的B-R缓冲溶液和适量的钴离子标准工作溶液后定容,室温下反应10 min,以350 nm为激发波长,440 nm为测定波长测定体系的相对荧光强度,结果表明,钴离子浓度在2×10^-6 ～7.6×10^-5mol/L范围内与CDs的相对荧光强度呈良好的线性关系,其线性回归方程为ΔF=1.008 7+0.031 25×10^-6 c(mol/L),相关系数r=0.998 5,方法检出限1.2×10^-7 mol/L。方法用于粉煤灰中痕量钴的测定,测定结果与国家标准方法GB/T 15922-2010相符,相对标准偏差(RSD,n=6)为0.9%～1.0%,加标回收率在98%～104%之间。

Determination of trace cobalt in fly ash by carbon dots fluorescence quenching method

Based on the significant quenching effect of cobalt ions on the water soluble fluorescent carbon dots (CDs) in B-R buffer solution at pH 6.80, a method was established for determination of cobalt ion by fluorescence quenching method. 0.5 mL of 3.6×10^-4 mol/L fluorescent CDs solution(in carbon), 1.0 mL of B-R buffer solution at pH 6.80 and proper amount of cobalt standard working solution were added successively into 5 mL colorimetric tube and diluted to the mark. After reaction at room temperature for 10 min, the relative fluorescence intensity of test system was determined at 440 nm with 350 nm as excitation wavelength. The results showed that the concentration of cobalt ion in range of 2×10^-6-7.6×10^-5mol/L showed good linear relationship with the relative fluorescence intensity of CDs. The equation of linear regression was ΔF=1.008 7+0.031 25×10^-6 c (mol/L) with correlation coefficient of r=0.998 5. The detection limit of method was 1.2×10^-7 mol/L. The proposed method was applied to the determination of trace cobalt in fly ash, and the results were consistent with those obtained by the standard method GB/T 15922-2010. The relative standard deviation (RSD, n=6) was 0.9%-1.0%. The recoveries were between 98% and 104%.