Ionisation Interferences:

In a few cases, high temperature flame might cause ionisation of some of the metal atoms, e.g., within case of sodium, it could be given as follows.

Na → Na⁺   + e^-

The Na⁺ ion possesses an emission spectrum of its own along with frequencies that are different from those of atomic spectrum of the Na atom. This decreases the radiant power of atomic emission. This interference could be eliminated through adding a huge quantity of a potassium salt to the standards as well as sample solutions. An addition of potassium salt suppresses the ionisation of sodium, as the potassium atom itself undergoes ionisation because of low ionisation energy. Therefore, the sodium atom emission is enhanced. This kind of interference is restricted to alkali metals.