Standard specimens for stain calibration: application to Romanowsky-Giemsa staining

Improving biological dyes and stains: quality testing versus standardization

This paper discusses the impact of both standardization and quality testing of dyes and stains in biology and medicine. After the brief review of why standardized dyes and strains are not presently available commercially, two types of testing and ways of improving dye quality are described. National or international organizations could be established to define standardization of dyes and stains. Standardization would be specifically defined as a list of physico-chemical parameters such as elaborated in this paper. Commercial batches of comparable quality may be labeled by the supplier as "standard dye," a procedure currently performed by the European Council for Clinical and Laboratory Standardization (ECCLS). Also recommended to improve dye quality is commercial dye testing by independent laboratories with subsequent certification for use. This sort of quality control is currently carried out in the United States by the Biological Stain Commission (BSC). The advantages and disadvantages of both techniques and the use of image analysis for the definition of standards are discussed. A combination of both the BSC testing protocols and the ECCLS standards should be established for extended quality control of biological dyes and stains.

Stability study of Azure B, Eosin Y and commercial Romanowsky Giemsa stock solutions using high performance liquid chromatography

The stability of Azure B and Eosin Y in stock solutions of the individual compounds as well as in mixtures of the two dyes was studied. The purpose of the study of these two essential constituents of the Romanowsky Giemsa stain, commonly used in cytology and histology, was to select a stable mixture as a definitive stock solution. Two specific high performance liquid chromatographic methods were used to monitor qualitative and quantitative changes in solutions. Several parameters influencing the stability of Azure B were examined e.g. the type of counter ion, the presence of Eosin Y and the type of solvent used. The second part focused on the stability of Eosin Y in mixtures with different cationic dyes submitted to high temperatures. In conclusion, an Azure B SCN-Eosin Y acid mixture in dimethylsulphoxide (concentrations 0.75% and 0.12%, respectively) was selected as being the most appropriate composition of a stock solution for the Romanowsky Giemsa stain.

Standardization of biological dyes and stains: pitfalls and possibilities

The present paper gives a review of the actual state of standardization of biological dyes and stains. In a first part general information is given on practical problems encountered by the routine user of dyes with special emphasis on dye contamination. Some theoretical aspects of standardization are discussed. The second part of the paper gives more detailed information on commercial batches of hematoxylin-eosin-, Giemsa- and Papanicolaou-stains and on their standardization. Special problems arising with the application of image analysis techniques are briefly mentioned. User-oriented specifications for the standardization of dyes, stains and staining procedures are given. Fluorescent dyes and dyes used in chromogenic reagents such as the Feulgen-Schiff reaction are not included in this review.

The standard Romanowsky-Giemsa stain in histology

A new and technically simple Romanowsky-Giemsa (RG) stain is proposed as a standardized technique for use in histology. An RG stock solution (pure azure B 7.5 g/l, eosin Y as eosinic acid 1.2 g/l in dimethylsulfoxide) is diluted to form the working solution with HEPES-buffer, pH 6. Staining time is 30-90 min after formol-calcium solution (or 2-4 hr after formaldehyde-organic acid mixtures). The resulting overstained sections are to be differentiated. A tannic acid-acetic acid combination in an isopropanol-water mixture was found to give optimum results within 100 sec. Subsequent dehydration is in isopropanol only. The staining pattern obtained is polychrome. The distribution of colors in detail is influenced by the modes of pre- and posttreatment. Of practical interest is the development of green and greenish blue colors on collagen fibrils which contrast strongly against the pink of sarcoplasm. For this and other reasons, this RG stain version seems suitable to replace the trichrome Gomori-type trichrome stains under appropriate processing conditions.