The present invention relates to a lysing reagent for use in the simultaneous automatic electronic enumeration and volumetric discrimination of different types of blood cells, such as leukocytes, thrombocytes, etc, in blood. Further, the present invention relates to a Coulter ( impedance) counting apparatus containing the lysing reagent, for example a Coulter counting apparatus with a disposable cartridge for characterizing cells suspended in a liquid, especially a self-contained disposable cartridge for single-use analysis, such as for single-use analysis of a small quantity of whole blood.
