On the proper use of the Soret band for hemoglobin detection in erythrocytic cells

Intracellular hemoglobin detection by light microscopy in the Soret band (414nm) is a sensitive means of correlating morphology and biochemical function in studies of erythrpoiesis. Correct application of the technique requires a light source with strong emission in the near ultra-violet, a filter with a pass-band at 414nm, a preparation of living cells or an unfixed smear, and a receiver that is sensitive to the Soret wavelength. The human eye is very insensitive to light at 414nm and quite sensitive to stray green light: it is consequently much inferior to a black and white television or camera film for viewing a Soret image. The appearance of hemoglobin during maturation of erythroid cells in human bone marrow can be detected with greater sensitivity by this method than by a peroxidase-benzidine stain and it is the only method applicable to living cells.