An Estimation of Plasma Vitamin A and the Vitamin A Absorption Test

Abstract

Heparinized plasma (4 ml.), 8 ml. absolute alcohol, and 8 ml. n-heptane (Hopkin and Williams, " free from aromatic hydrocarbons "), are shaken in a mechanical shaker for 15 minutes. No troublesome emulsions are formed and the layers are allowed to separate. The heptane layer is pipetted off and divided into two approximately equal portions. One portion in a soda-glass on July 21,