抄録
When retinoic acid in chloroform solution was reacted with sulfuric acid, a red color (λ_<max> of 540 mμ) was produced in the sulfuric acid layer ; E^<1%>_<1cm>(540 mμ) 1240. The color was stable for 20 minutes but upon the addition of water, the color produced by retinoic acid faded away rapidly. This color reaction of retinoic acid was more reproducible than SbCl_3-reaction. Recovery tests of retinoic acid by using rat liver homogenates were proved to be satisfactory for routine determination.
