Determination of Li, Na, Mg, K, Ca and Fe with ICP-MS using cold plasma conditions

Some important analytes in ICP-MS are interfered by plasma argon or argon s pecies, such as ArO+ and Fe-56, Ar-40 and K or Ca. One approach to overcome this interference is the use of reduced forward power and a metal shield i nserted between torch and load coil. These so called cold plasma conditions reduce the background caused by argon species and the formerly interfered analytes can be easily detected in the ng/g-range. Other elements in the lo wer mass region also profit from these conditions even when they are not in terfered in normal plasma mode. The limits of detection are improved due to reduced background noise level and enhanced ion transmission. On the other hand, the reduced power fed to the plasma lowers the analytical performanc e and makes it susceptible to matrix effects. Elements of higher mass gener ally show higher detection limits compared to normal plasma mode.