A standardized differential stain for hematology.

A stain composed of purified Azure B and Eosin Y has been developed for use in conjunction with an automated stainer. This system provides the consistency in chromatic properties required for automated blood-cell analysis by pattern recognition systems. The stain represents a marked improvement in stability over those presently used with differential analyzers, but it is also an important advance toward a standardized stain for general hematological use. The purity of the component dyes, the stability of the final stain and the dependence of staining intensity on the stain/buffer ratio and dye concentration are discussed.