catalytic activity concentration; catalytic concentration #864OIML 1. The derived coherent SI unit is the mole per 0 second per cubic metre (mol/(s × m3)), also called kat/m3. In laboratory medicine the mole per second per litre (mol/(s × L)) is also frequently used. 2. Throughout this Recommendation the “component” is an enzyme and the “original system” can be, e.g., the plasma of a blood sample. [ISO/DIS 18153, clause 3.3]