流动注射荧光猝灭法测定磷酸二氢盐

Phosphate Determination Based on Fluorescence Quench of Cerium(Ⅲ) Complex with Flow-Injection Analysis

中文关键词:  流动注射分析  荧光猝灭  Ce(Ⅲ)  磷酸二氢盐

英文关键词:flow injection analysis  fluorescent quenching  cerium(Ⅲ)  phosphate

中文摘要:

      在pH=5.4的(CH₂)₆N₄-HCl缓冲溶液中,建立Ce(Ⅲ)-NaClH₂PO₄^-三元荧光熄灭体系,结合流动注射技术和荧光猝灭定量数学模型Ln(F₀/F)=LnK_MF+LnK_e-LnK_F+Ln[M],考察Ce(Ⅲ)的阳离子型体测定HH₂PO₄^-的可行性和适用性.实验表明:在20℃,pH=4.0～6.0时,Ce(Ⅲ)的阳离子型体与磷酸根反应,荧光猝灭程度显著;当注射泵转速为70r/min,样品测定速度为50h^-1,NaCl浓度为0.20～0.30mol/L时,H2PO4-的测定线性浓度区间为0.20～1.80μg/mL,检测限LOD(3δ)=0.003μg/mL,样品回收率为97.3%～99.0%.

英文摘要:

      The fluorescence spectra of cerium(Ⅲ) emitted at 358 nm exited at 254 nm in sodium chloride medium. A new FIA method using fluorescent quenching for the determination of phosphate was proposed. It was based on the ability of phosphate to inhibit the formation of a strongly fluorescent complex of cerium(Ⅲ) with NaCl in (CH₂)₆N₄-HCl buffer solution (pH=5.4), for the electrostatic interaction of the positive species of Ce(Ⅲ) in water with the negative charge of phosphate. With the analysis model Ln(F₀/F)=LnK_MF+LnK_e-LnK_F+Ln[M] based fluorescent quenching, optimal chemical conditions for fluorescent quenching of the CeCl_n^(3-n)- (n=1～6) positive species by phosphates in samples were studied. The measurement throughput was 50 h^-1, and the concentration ranges of sodium chloride were 0.20～0.30 mol/L. Within the range of H₂PO₄^- from 0.20 to 1.80 μg/mL, calibration graph was obtained and the limit of detection was 0.003 μg/mL. The recoveries of artificial samples ranged from 97.3% to 99.0%.