Staining properties of oil red O and a method of partial purification of the commercial product.

SEVERAL OIL-SOLUBLE aniline dyes have been used to demonstrate lipoproteins on paper electrophoresis strips (1-4). Durrum et al. (5) found oil red 0 superior to others. Jencks and Durrum (6) described a technic for determining the amount of this dye taken up by alpha and beta sections of serum paper electrophoresis strips, showed that there were several components in commercial oil red 0, and pointed out some of the limitations of this method. While treating paper (7) and starch-gel electrophoresis strips (8) with commercial oil red 0 for demonstration of lipoproteins, we observed that this solution also stained albumin and globulins. Since the lipoproteins and the proteins usually are superimposed on the electrophoresis strips, we considered it important to attempt to purify this dye. Described below is a simple method based on differences in solubility for fractionation of crude oil red 0 and partial removal of its protein-staining components. Also presented are some indications of the staining properties of various fractions of the dye.