Estimation of vitamin A and carotene in human blood

Abstract

The methods used for extracting carotene and vit. A and estimating the colors of carotene and vit. A were discussed. A simple photoelectric colorimeter with filters with maxima at 440 m[mu] and 620 m[mu] for carotene, and the Carr Price reaction were used respectively. Pure [beta] carotene and vit. A 2-naphthoate were used for calibrating. A comparison was made between 4 different methods of extracting carotene and vit. A from serum or plasma: (1) Saponifying and extracting with ether; (2) saponifying and extracting with light petroleum; (3) precipitation with alc. and extracting with ether; (4) precipitation with alc. and extracting with light petroleum. Results show that method (4) is the simplest as well as the best. No. (2) gives consistently poor results. A preliminary series of results on healthy volunteers with normal dark adaptation gives a range of 50-240 [mu]g. (avg. 120 [mu]g.) for carotene and 72-157 I.U. (avg. 113 I.U.) for vit. A per 100 cc. serum or plasma.