Measurement and Results - Cesium (Cs) and rubidium (Rb) analyses by ICP-OES

Cesium and rubidium analyses by ICP-OES can be challenging as the plasma is designed to produce ions, whereas preferred Cs and Rb emission lines are atomic. In other words, the plasma is converting most of the Cs and Rb to ions when your analysis would benefit from these elements remaining in the atomic state. This issue is exacerbated by the fact that alkali metals ionize easily. The general approach to deal with this effect is to add an ionization buffer, which floods the plasma with an excess of electrons and reduces the relative abundance of alkali metal ions. Therefore, ionization buffers need to be sources of readily available electrons, and not surprisingly, tend to be vey pure single-element solutions of an alkali metal. The basic concept is that you sacrifice the measurement of one of the alkali metals (Li, Na, K, Rb, or Cs) and use it as an ionization buffer. We follow this approach at IV by adding 500 ppm Cs to our ICP-OES solutions to improve the measurement of Li, Na, and K. For analyses of IV-ICPMS-71A we would recommend using Li as the ionization buffer as it's not present in this standard, and our stock product LINB2 (20,000 ppm Li in HNO3) would be ideal for this approach.