Abstract: Hemotological analyses for hemoglobin and for three part white cell differential count. The dilution step is performed off line from the precisely controlled lysing and cell size measurement steps, thereby substantially reducing initial investment costs while retaining analytical accuracies. Simultaneous mixing means are provided for the lysing reagent addition step.

Abstract: Improved reagents and methods for obtaining distinct volumetric differentiation of platelets, erythocytes and certain leukocyute subpopulations are disclosed. 1,3-dimethylurea is disclosed as a cell stabilizing agent for use in the blood diluent reagent. A hematology analyzer detergent is described wherein the addition of a wetting agent to the diluent of the instant invention provides the necessary attributes of an automatic analyzer detergent. The lysing reagent exploits the selective and intrinsically gentle lytic qualities of the dodecyl quaternary ammonium salt. The improved method modifies the leukocytes so that the frequent lymphocyte and neutrophil subpopulations are well separated on a volume scale, permitting quantitative evaluation of infrequent and rare leukocyte subpopulations as well as improved enumeration of the lymphocytes and neutrophils.