Preparation of Schiff-type dye-SO2 reagents with phosphoric acid and their cytochemical properties

A new method employing phosphoric acid in place of hydrochloric acid for the preparation of azure A-SO2 and toluidine blue O-SO2 has been described in this communication. It has been found that o-phosphoric acid in a weak concentration can be a suitable substitute for hydrochloric acid in the preparation of these dye-SO2 reagents. These dye-reagents produce excellent blue nuclei in human uterine tumour. Toluidine blue O-SO2 fortified with an amino aicd, glycine also produces excellent blue chromosomes in the squash preparations of grasshopper testes fixed in acetic acid-alcohol. The shelf-life of these two dye-reagents has also been presented herein.