Quantities and units for centrifugation in the clinical laboratory

The centrifuge is widely used in clinical laboratories for the separation of components. For example in laboratories performing biochemical analyses on body fluids it is routinely used to separate blood cells from plasma, to separate sediment from urine, to measure the volume fraction of erythrocytes in blood (the haematocrit), and to separate bound from free components in protein binding and immunoprocedures. Less routinely, centrifugation is used for separation of lipoproteins in reference procedures for their measurement, separation of cellular components, and separation of DNA fragments. Various quantities are used for the description and the calculation of the separation processes at centrifugation. The aim of this document is to provide manufacturers and users of centrifuges with a list of quantities and units for centrifugation consistent with the International System of Units, SI, and standards of the International Organization for Standardization (ISO).