同位素气溶胶加入法ICP-MS在线分析单粒子中的铀总量

On-Line Quantitative Analysis of Uranium in Individual Particle With ICP-MS Using Isotopic Aerosol Particles Addition Calibration Method

本研究发展了一种ICP-MS同位素气溶胶加入法,可实时标定仪器灵敏度,对气溶胶粒子进行在线定量分析。介绍了同位素气溶胶加入法的原理和参数测量方法,并应用该方法对人工发生的天然铀单粒子中的铀总量进行在线分析,考察方法的可行性。实验结果表明,该方法测得的单粒子中238U原子数的精度为5.6%,比气溶胶发生器给出的计算结果偏大19%,讨论了偏差的可能主要来源。

In order to calibrate the instrument in real-time for on-line quantitative analysis of airborne particles with ICP-MS,an isotopic aerosol particle addition calibration method was developed in our laboratory.In this paper,the method was introduced in detail and validated using artificially generated particle containing uranium.First,aerosol generation efficiency and solution uptake rate of nebulization sample introduction system were determined accurately through experiments.Natural uranium standard solution was prepared for generation of micron-size and monodisperse particle by a commercial Vibrating Orifice Aerosol Generator（VOAG）.Isotope was selected to overcome the mass discrimination effect.233U standard solution was prepared for nebulization of 233U containing particles.The discrete 238U containing particle and continuous 233U containing droplets were mixed together,desolvated in a membrane dryer,and introduced into ICP-MS for on-line analysis.Peak-jump mode was used to monitor 233U ion intensity and 238U ion count.Instrument sensitivity for 233U was calibrated in real-time.After mass discrimination correction,atom number of 238U in individual particle was determined.Results show precision of measured 238U atom number in individual particle is 5.6%.The discrepancy with the calculated value based on VOAG operation parameters is 19% and the possible reasons were discussed preliminarily.