Ionization Buffers are used to increase the free electron population in flame emission or absorbption and thereby supress ionozation interference effects of many ions in high temperature flames such as nitrous oxide - acetylene.
While the alkali metals are known to be ionized at various degrees, many metals including aluminium and silicon are ionized to an appreciable extent in a nitrous oxide - acetylene flame. Ionization buffers are always recommended with the nitrous oxide-acetylene flame.
It is of interest to note that the ionization potential of lanthanum (5.6eV) is very close to that of lithium (5.39eV).
Therefore , lanthanum acts as an ionzation buffer as well as a releasing agent for the alkaline earth metals, silicon, and aluminium.
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