Chromatographic Estimation of Vitamin A in Mixed Feeds

Preformed Vitamin A in Mixed Feeds

“…Chromatographic adsorption methods have been used in the preparation of extracts of vitamin A in order to free them of interfering substances. Floridin earth (1), calcium phosphate (8), sodium carbonate (5), charcoal (6), bone ash (8), alumina (18), and magnesia ( 16) have been used as adsorbents. Some of the materials retain vitamin A and pass the remaining substances; the vitamin A present is then estimated by difference.…”

“…Inasmuch as whole and saponified extracts of feeds have been used in chromatographic work (3,5,16), it seemed advisable to determine the effect of saponification on the recovery of vitamin A from the column. Some samples of feed extracts containing vitamin A oils were saponified and then chromatographed; the whole extract was used as a control.…”

Determination of Carotene in Plant Materials

“…Of the LTHOUGH sodium dieth.v ldithiocarbamate has been used extensively for the colorimetric determination of copper, the reagent possesses the disadvantage that it forms an insoluble copper salt and requires the use of gum arabio for stabilization of the colloidal suspension (6) or extraction with a suitable organic solvent (5) before colorimetric comparison can be made.…”

Food

“…Methods have been described for the determination of the vitamin A-active pigment, carotene, itself (63,147,SOI,373) in alfalfa and similar grasses, and together with preformed vitamin A in mixed feeds (86,265). By the appropriate choice of the developing solvent it has been found possible to separate ßcarotene from certain of its stereoisomers (31).…”