Staining properties and stability of a standardised Romanowsky stain

An evaluation of the standardised Romanowsky stain of Marshall et al. has been made in a routine haematology laboratory. It was noted that this stain had several advantages over the May-Grünwald Giemsa stain used in most British laboratories. These advantages include ease and speed of preparation, a shorter staining time, and reproducibility of results. These results are described in detail. The stability of the stock stain solution and of the 'working' stain (stock + buffer) has been studied by, respectively, thin-layer chromatography and visible spectroscopy. No change was detected in the composition of the stock solution at ambient temperature over a period of six months. Stability was unaffected by the composition of the container (polyethylene, PyrexTM, or soda-glass) or by daylight. The 'working' solution was stable for 3 hours. Thereafter a precipitate is formed, consisting of thiazine dyes and eosin in a molar ratio of approximately 2:1.