BEHAVIOR OF DOG SERUM DYED WITH BRILLIANT VITAL RED OR EVANS BLUE TOWARD PRECIPITATION WITH ETHANOL

Abstract

Recovery of Brilliant Vital Red and T-1824 in supernatants from ethanol precipitation of serum, plasma, and pure albumin solns. has been studied in relation to original concn. of dye and concn. of precipitating ethanol. Hamilton''s ethanol method for colorimetric analysis of serum for BVR was confirmed by and adapted to Beckman spectrophotometry. Readings should be made at 508 m[mu]. If the concn. of precipitating ethanol is reduced to about 88%, almost all of the BVR appears in the supernatant. At this concn. the method is also applicable to T-1824, about 80% being recoverable. Hemoglobin as such is completely precipitated. Under conditions not yet adequately described, it may liberate into the supernatant traces of a substance which spectrophotometrically resembles heme. Correction for this, if present, is made by reading at its 404 m[mu] absorption peak. Its extraction is minimized and its spectrum is stabilized by the addition of about 1 g. of Na metabisulfite to each liter of precipitating ethanol. Saline solns. of crystalline serum albumin give a much smaller recovery of dye in the supernatant than similarly treated plasmas. It is argued that the behavior described is due not so much to the relationship between protein and dye as to the apparent solvent power of the respective supernatants for the dyes, and to their ability to stabilize the dyes in soln.