K-FACTOR
Initial probe work by Castaing was metallurgical and the standards were pure elements, and so the K-ratio was defined relative to a pure element standards. In the situations where the standard is not the pure element, a means to use the normal form K-ratio is to normalize the standard, using the standard k-factor. This is the concentration of the element in the standard (as a fraction) divided by the ZAF correction of the element in the standard. See also raw k-ratio, unknown k-ratio and ZAF. The expression is :
where :
is the concentration of element A in the standard
is the ZAF correction for element A in the standard