Abstract
The author has previously given a method of eliminating iron from silica gel of thin-layer chromatographic use with a homogeneous mixture of acetone, hydrochloric acid and methyl iso-butyl ketone. Another method is presented in this paper in which hydrochloric acid and methyl iso-butyl ketone are employed as in the manner of usual liquid-liquid extraction. Silica gel was dipped into 6 M hydrochloric acid in a glass-stoppered centrifugal tube and one-third volume of methyl iso-butyl ketone was put into the vessel. After shaking for 1.5 hrs., the iron attached on the silica gel was dissolved in the acid and transferred into the organic solvent. As much as 23% of total iron contained in the silica gel (estimated as 4×10-3%) was removed in the organic sofvent by a single extraction and reached 25% after quintuple extractions. The iron attached on the surface of the silica gel was eliminated readily by the above treatment and no interference appeared in chromatographic developement. The amount of the iron released from the silica gel was estimated by photometric method on red iron(III) thiocyanate was in the organic solvent.
