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, 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.