A Concave Concentration Gradient of Methanol in Chloroform Employed in Elution of Lipids from Silicic Acid

Abstract

IN several laboratories, where whole lipid extracts are chromatographed on silicic acid in chloroform-methanol, experience has suggested the need for continuous concave gradient elution. Devices are described in the literature for producing concave gradients of solutes in aqueous solution, but they are unsuitable for chloroform-methanol mixtures: they fail for liquids of unequal density, waste eluent, or are not easily constructed without rubber joints, greased stopcocks, etc. Hitherto, therefore, discontinuous gradients or continuous linear or convex gradients have been used for elution of lipids.