Abstract

The extraction and estimation of uranin (fluorescein sodium) in plasma is described. Heparin-plasma containing uranin is digested with crude ficin and extracted with acid n-pentanol. The supernatant fluid is re-extracted with N NaOH and, after volume adjustment, read against a uranin standard in a fluorimeter with appropriate filters. It appears reliable within 4% at concentrations as low as 10⁻⁸ g./ml.