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

在pH =5 .4的 (CH2 ) 6N4 HCl缓冲溶液中 ,建立Ce(Ⅲ ) NaCl H2 PO4 -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) =LnKMF+LnKe-LnKF+Ln[M],考察Ce(Ⅲ )的阳离子型体测定H2 PO4 -的可行性和适用性 .实验表明 :在 2 0℃ ,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 5 0h-1,NaCl浓度为 0 .2 0～ 0 .30mol/L时 ,H2 PO4 -的测定线性浓度区间为 0 .2 0～1.80 μg/mL ,检测限LOD(3δ) =0 .0 0 3μg/mL ,样品回收率为 97.3 %～ 99.0 %

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 (CH\-2)\-6N\-4\+- 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( F \-0/ F )=LnK\- MF +LnK\-e-LnK\-F+Ln 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 H\-2PO\-4\+- 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 %.