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Two-dimensional chromatography on commercially available silica gel-loaded paper for the microanalysis of polar lipids from various tissues is described. All common phospholipids and their lyso derivatives can be reproducibly separated. As many as 22 lipid components were separated on a single chromatogram. Improved methods for staining lipids and for determining phosphorus in the chromatographic spots are reported.

Commercial silica gel loaded filter paper has been found to give good separations of neutral lipids and phospholipids. Unidimensional or two-dimensional chromatography can be used. Rat liver lipids and C14-algae lipids were studied. An advantage over thin-layer chromatography is that several spot tests can be applied on the same chromatogram.

Improvements in the detection of phospholipids on paper chromatograms by neutron activation (with the formation of P32-compounds) have been made. Formaldehyde-treated papers were subjected to low neutron dosage after chromatographic development and the resulting radioactive spots were detected by automatic scanning and autoradiography.

The separation of dog serum lipoproteins by ultracentrifugation at a density of 1.063 is hindered by the failure of the high density fraction to accumulate in the bottom portion of the centrifuge tube. This phenomenon interferes with the quantitative recovery of pure low density lipoproteins. By paper electrophoresis, a lipid-containing protein with the mobility of a β-globulin was detected in the lowest layer of the centrifuge tube. Comparison of the preparative ultracentrifuge technique with that of dextran sulfate precipitation of β-lipoproteins revealed the suit ability of the latter procedure for the quantitative separation of β-lipoproteins. The dextran sulfate β-lipoprotein precipitate was shown to be free from α-lipoprotein by paper electrophoresis.

A rapid chromatographic procedure was developed for the separation of sphingomyelin, phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl serine, phosphatidyl inositol, and free fatty acids on glass paper coated with sodium silicate. In addition, phosphatidyl choline and sphingomyelin were determined quantitatively by densitometry of the charred chromatogram, which was obtained by spraying the developed chromatogram with sulfuric acid and heating in an oven. The separation of phosphatides on sodium silicate-treated glass paper is more rapid than on silicic acid-impregnated paper, and the former is simpler to prepare. Preliminary application of this quantitative technique to human serum indicates that it may have a wide adaptability for the determination of phospholipids in natural products.

Chromatographic procedures for the detection and evaluation of oxygenated fatty acids are described. Emphasis has been placed on epoxy acids, but these methods promise to be of great value in studies of all classes of oxygenated acids. Paper chromatography of fatty acids and their esters has been developed for the examination of mixtures containing oxygenated derivatives. The method of adsorption chromatography on thin layers of silicic acid has been shown to be a powerful tool in studies of epoxy acids and hydroxy acids. Gas-liquid chromatography (GLC) of epoxy esters has been studied using both polar and nonpolar columns and has great utility in the detection and analysis of these compounds in mixtures. These methods have been applied to the examination of the epoxy components of six seed oils. Thin-layer and GLC proved particularly useful in this study and together demonstrated the presence of at least three distinct epoxy acids in each of these oils. Some conclusions as to the probable structures of these epoxy components are presented on the basis of their chromatographic characteristics in relation to known substances.

A rapid, sensitive method for the determination of sterols is described. Microgram samples are spotted on impregnated glass fiber paper, chromatographed for 7 minutes, dried, sprayed with sulfuric acid, and charred by heating. The amount of char formed is measured by densitometry. Values obtained for cholesterol in the serum are in agreement with those obtained by the Sobel-Mayer method. The method has been adapted to the determination of cholesterol in 10 μl. of plasma, and to the determination of standard solutions of other sterols.

The precipitation by trichloroacetic acid (TCA) of radioactive lipids on disks of filter-paper, followed by extraction with TCA and water to remove soluble radioactive precursors, provides the means for a convenient assay for lipid biosynthesis. Large numbers of disks can be washed in the same vessel, dried, and assayed for radioactivity with liquid scintillation counting equipment. Extraction of disks with lipid solvents provides a convenient control for the possible presence of TCA- and water-insoluble, nonlipid products. The application of the method to the assay of cyclopropane fatty acid synthetase is shown.

A new paper electrophoretic method for the separation of bile acids into five groups, (1) unconjugated, (2) glycine conjugates and (3) taurine conjugates, and (4) and (5) the respective monosulfates, is described. Rapid and accurate qualitative and quantitative estimations of each group are obtained by densitometry after internal standardization and phosphomolybdate color development. The technique can be done in the routine clinical laboratory and is useful for the detection of diseases affecting the enterohepatic circulation of bile acids.