clearance, Δ V Δ t

Also contains definition of: volume rate

Product of the concentration of a component in an output system and the volume flow rate of that output system divided by the concentration of this component in the input system.
Note:
The term mean volume rate is recommended for this quantity.
See also: clearance (in toxicology)
Source:
PAC, 1996, 68, 957 (Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)) on page 966