Thin-layer chromatography of ceramides

Ceramides with mono-, di-, and trihydroxy long-chain bases, and normal (saturated and unsaturated), branched-chain, and 2-hydroxy fatty acids have been analyzed by thin-layer chromatography. In most cases the compounds were also run as acetates. Borate, arsenite, and silver ions were used as complexing agents, and the effects of number, position, and stereochemistry of hydroxy groups, and of unsaturation, were studied. The results are discussed in view of analysis of natural ceramide species.     

Thin-layer chromatography of the phosphoinositides

Thin-layer chromatography for the separation of mono-, di-, and triphosphoinositides (0.3-3 micro g total phosphorus) is described.     

Thin-layer chromatography of hyaluronate oligosaccharides

Odd- and even-numbered hyaluronate oligosaccharides with N-acetylglucosamine, glucuronic acid, or 4,5-unsaturated glucuronic acid at their nonreducing ends were separated by thin-layer chromatography, using silica gel and a solvent system of isopropanol-water (66 : 34) containing 0.05 M NaCl. In the isopropanol system, small amounts of electrolytes were necessary for the resolution of each oligosaccharide.     

Thin-layer chromatography of hydroxamic acids

The separation of very short-chain from long-chain fatty acyl hydroxamates by thin-layer chromatography is described. The detection limit was 2 micrograms.     

Thin-layer chromatography of thiosulfonate anions

Organic thiosulfonates of the form RS(O₂)S^? can be separated from the characteristic contaminants in synthetic preparations by thin-layer chromatography on silica gel. Thiosulfonates and sulfinates can both be visualized, and differentiated, by treatment of plates with a FeCl₃ reagent in acetone. Data are presented for seven aromatic and six aliphatic thiosulfonate anions and the corresponding sulfonates and sulfinates. With exception of the series related to cysteic acid, R_f values are always in the order RS(O)₂S^? > RSO₃^? > RSO₂^?.     

Thin-layer chromatography of tissue lipids without extraction

Frozen tissue sections were applied directly to silica gel plates, and the lipids were separated by developing the plates in different solvent systems. Quantitation of the lipid classes was achieved by direct transmission densitometry after the plates were treated with a chromic acid-sulfuric acid spray.     

The analysis of aflatoxins by high-performance liquid chromatography.

The potential of high-performance liquid chromatography as a technique for separating aflatoxins B₁ B₂, G₁, G₂, B_2a, Q₁, M₁, P₁, aflatoxicol, and a degradation product of aflatoxin B₁, 2,3-dihydrodiol, has been assessed. A microparticulate silica adsorption column used with a 1:1 chloroform -dichloromethane eluant provided good resolution of aflatoxins B₁, B₂, G₁, and G₂ but the addition of 1% propan-2-ol was necessary for the elution of aflatoxins M₁ and Q₁. By selecting appropriate solvent mixtures, good resolution of all of the aflatoxins studied was obtained using columns containing an octadecyl (C₁₈) reversed-phase bonded to a microparticulate support. Details are given for resolving: (1) aflatoxins B₁, B₂, G₁, and G₂ using a 5% tetrahydrofuran-15% dimethylformamide in water eluant and (2) aflatoxins B₁ B_2a, Q₁ M₁ P₁ aflatoxicol, and a product of aflatoxin B₁ 2,3-dihydrodiol treated with Tris-buffer, using either 15% dimethylformamide in water or 10% tetrahydrofuran in water as eluant.     

Thin-layer chromatography and high-performance thin-layer chromatography of [3H]metabolites of 20-hydroxyecdysone

Normal-phase and reversed-phase thin-layer chromatographic systems for the separation and analysis of [³H]metabolites of 20-hydroxyecdysone have been developed. These include separations involving multiple development (in one or more solvent systems), two dimensional techniques, reversed-phase and ion-pair chromatography. Using these systems, the resolution and identification of the major metabolites of 20-hydroxyecdysone, produced following the injection of tritiated hormone into adult male Locusta migratoria, have been demonstrated.     

Immunoaffinity column chromatography for detection of total aflatoxins in experimental situations

Summary The Aflatest^R immunoaffinity method has been successfully used to measure total aflatoxins in experimental situations. A high level of correlation was achieved between the immunoaffinity separation and fluorimetric quantification of total aflatoxins and traditional solvent extraction and quantification by HPLC methods.     

Thin-layer chromatography of sterols on neutral alumina impregnated with silver nitrate

Thin-layer chromatography for the rapid separation of several sterols on neutral alumina impregnated with silver nitrate is described. The method is particularly effective for sterols that differ in the number and location of olefinic bonds.