Zirconia colloid analysis by single particle inductively coupled plasma–mass spectrometry

Single particle analysis of zirconia colloids in water has been performed by inductively coupled plasma–mass spectrometry (ICP–MS). The transient signal induced by the flash of ions due to the ionisation of a zirconia colloidal particle in the plasma torch can be detected and measured for selected zirconium ion masses by the mass spectrometer. The intensity of the MS signal is recorded in time scan. The peaks recorded are analysed as a function of the particle size, and the fraction of the studied element or isotope in the colloid phase. The frequency of the flashes is directly proportional to the concentration of particles in the colloidal suspension. After developing the theoretical aspect on detection, composition and intensity of ion flashes generated by colloid ionisation in the plasma torch, tests were performed on model zirconia colloids and on silica colloids coated with zirconia. This feasibility study also describes the experimental conditions and the choice of isotopes to detect zirconia colloids in a single particle analysis mode.