Improved Stability of Methanolic Wright's Stain with Additive Reagents

Abstract

Additive reagents have been investigated to improve the stability of methanolic Wright's stain. The addition of ammonium halides, monoalkylamine hydrochlorides, dialkylamine hydrochlorides or trialkylamine hydrochlorides to methanolic Wright's stain was found to enhance the stability of stain components in methanol. No change in performance is observed with these additives present. Random precipitation in the stain solution was still observed with the addition of ammonium halides and monoalkylamine hydrochlorides. No precipitation was found in stain solutions containing hydrochlorides of most dialkylamines and trialkylamines. Of the compounds evaluated, 0.6% diethylamine hydrochloride added to methanolic stain solutions produced the most desirable overall results. Mechanisms of stabilization and precipitation in these stain solutions are proposed. Essentially, separation of the thiazine-eosinate ion pair through interaction with an appropriate additive increases stain stability. The solubilities of thiazine-eosinate or additive cation-eosinate ion pairs in methanol determine the formation of precipitate in such stain solutions.

Stability of azure B–eosin Y staining solutions

“…Several pure azure B dyes became commercially available; specifications of these dyes and staining technique using them were recommended recently by the International Committee for Standardization in Haernatology ( 1984). However, the combination of a methylene blue derivative (a cationic dye) and eosin (an anionic dye) forms an unstable solution in a water containing medium (Liao et al, 1981); as the stability of a staining solution is of great practical importance for daily routine use, an analysis was carried out of the stability of the azure J3-eosin Y staining solution. For this purpose buffy coat slides were stained in solutions of varying composition, freshly prepared and 4 and 8 h after preparation.…”