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

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, desolated 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. (authors)