SECONDARY STANDARD
A standard which is not assigned as a primary standard for a given element (that is, not directly used in the quantitative calculation of unknowns). However, it is useful, if the secondary standard contains a known quantity of the analyzed element, to check the quality of the secondary analysis can be judged by observing the "%VAR" line when an analysis is performed. The "%VAR" is calculated as follows :
where :
is the published concentration of the element
is the measured average concentration of the element