芯片式微型流通池顺序注射化学发光法测定水中的亚硝酸根

Determination of Nitrite in Water Samples by Sequential InjectionAnalysis with Chemiluminescence Detection on Chip Flow Cell

设计了一种芯片式流通池和顺序注射技术联用,基于在酸性介质中NO-2与H2O2反应生成不稳定的过氧亚硝酸,在碱性环境中猝灭为过氧亚硝酸盐迅速分解产生化学发光的原理,测定了环境水中痕量的亚硝酸根离子浓度;和常规的顺序注射进样方式不同,将流通池作为储存管的一部分,在顺序注射进样条件下可以迅速跟踪捕捉化学发光反应信号;采用阳离子交换树脂进行水样前处理,消除了阳离子的干扰。NO-2浓度在1×10-6～1×10-4mol·L-1范围内和发光强度呈线性关系。方法的检测限为68×10-7mol·L-1。对浓度为1×10-5mol·L-1的试液,11次重复测量的相对标准偏差为27%,回收率在90%～99%之间,分析频率为80h-1。

A sequential injection chemiluminescence's system using a chip flow cell was described for the determination of trace amount of nitrite in water samples. Nitride reacted with hydrogen peroxide to form peroxynitrous acid in sulfuric acid medium, which was an unstable in acid medium and subsequently was quenched into peroxynitrite in basic solution. During the composition of peroxynitrite the chemiluminescence intensity was enhanced with the presence of uranin and ethyldimethylcetylammonium bromide. The reaction coil (flow cell) and holding coil was combined for tracking the emission signal. The experimental parameters including physical and chemical parameter were optimized. The interference of cations in water samples was eliminated by passing previously the sample solution trough a cation-exchange column. The linear range of the calibration graph was obtained from 1 X 10(-6) to 1 X 10(-4) mol.L-1 with a correlation coefficient of 0.999 8. The detection limit at 95% confidence was 6.8 X 10(-7) mol.L-1. The relative standard deviation at 1 X 10(-5) mol.L-1 nitrite level was 2.7 %, and the recovery of 90 %-99 % and the sampling frequency of 80 h(-1) were obtained.