Thin-layer chromatography

About: Thin-layer chromatography is a research topic. Over the lifetime, 7494 publications have been published within this topic receiving 124179 citations. The topic is also known as: TLC.

A Method for the Measurement of Aldosterone in Peripheral Plasma Using 3H-acetic Anhydride

Abstract: A double isotope derivative method suitable for the estimation of aldosterone in human peripheral plasma has been developed. 3H-acetic anhydride was used as labeled reagent (1050 mc/mmole) and 4-14C-aldosterone (46 mc/mmole; 0.8 mμg added to the sample) as indicator. Only 0.25 μl (2.5 mc) acetic anhydride in 5μl benzene is required per reaction as aldosterone 21-monoacetate is the initial derivative formed. Purification is achieved by 2-dimensional silica gel thin layer chromatography of aldosterone 21-monoacetate and of the 18,21-diacetate then formed using nonisotopic acetic anhydride, followed by 2 paper chromatograms of the diacetate. The over-all recovery of the method with these 4 chromatographic steps is 31 ±9 (sd)%. Adequate specificity of the method was shown by no significant change in the values when aliquots of all samples estimated were further purified by acid hydrolysis of the diacetate to the 21-monoacetate followed by paper chromatography, and then after oxidation of the monoacet...

Determination of the hydrothermal degradation products of D-(U-14C) glucose and D-(U-14C) fructose by TLC

Abstract: The hydrothermal degradation was examined using D-(U-14C) glucose and D-(U-14C) fructose. By thin layer chromatography with methylene chloride, tetrahydrofuran (THF), acetic acid −60∶20∶20 as a mobile phase it was, possible to separate and identify the carbohydrates and their reaction products, glyceraldehyde, dihydroxyacetone, methylglyoxal, glycolaldehyde, 5-hydroxymethylfurfural and furfural. Up to 99% of the initial activity was determined by scintillation counting of the TL-chromatograms. A reaction scheme for the hydrothermal degradation of glucose and fructose was obtained from these results.

A Remarkable Ring Contraction En Route to the Chartelline Alkaloids

Abstract: General procedures. All reactions were carried out under an inert nitrogen atmosphere with dry solvents under anhydrous conditions unless otherwise stated. Dry tetrahydrofuran (THF), toluene, benzene, dichloromethane (CH2Cl2), methanol (MeOH), N,N-dimethylformamide (DMF), and triethylamine (Et3N) were obtained by passing these previously degassed solvents through activated alumina columns. Reagents were purchased at the highest commercial quality and used without further purification, unless otherwise stated. Copper(I) iodide was freshly purified from refluxing saturated aqueous NaI solution (aqueous). Yields refer to chromatographically and spectroscopically (H NMR) homogeneous materials, unless otherwise stated. Reactions were monitored by thin layer chromatography (TLC) carried out on 0.25 mm E. Merck silica gel plates (60F-254) using UV light as the visualizing agent and an acidic mixture of anisaldehyde or phosphomolybdic acid or basic aqueous potassium permangante (KMnO4) and heat as developing agents. E. Merck silica gel (60, particle size 0.043–0.063 mm) was used for flash column chromatography. Preparative thin layer chromatography (PTLC) separations were carried out on 0.25 or 0.5 mm E. Merck silica gel plates (60F-254). NMR spectra were recorded on Bruker DRX-600, DRX-500, and AMX-400 or Varian Inova-400 instruments and calibrated using residual undeuterated solvent as an internal reference. The following abbreviations were used to explain the multiplicities: s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet, b = broad. High-resolution mass spectra (HRMS) were recorded on Agilent LC/MSD TOF time-of-flight mass spectrometer by electrospray ionization time of flight reflectron experiments. IR spectra were recorded on a Perkin Elmer Spectrum BX FTIR spectrometer. Melting points were recorded on a Fisher-Johns 12-144 melting point apparatus.

Quantification of Three Cholesterol Oxidation Products in Raw Meat and Chicken

Abstract: Raw veal, beef, pork, and chicken muscle tissues were extracted by a modified dry column procedure in which silicic acid was incorporated in the trap of the column. This method separated cholesterol derivatives from the bulk of neutral lipids, phospholipids and cholesterol. Isolation of sterols by preparative thin layer chromatography followed by quantification by direct on-column capillary gas chromatography permitted measurement of 7-ketocholesterol, cholesterol 5α, 6α-epoxide, and cholesterol 5β 6β-epoxide at concentrations less than 1 ppm. All muscle tissues contained the three cholesterol products in measurable quantities. 7-Ketocholesterol constituted more than 50% of the oxidation products in all samples.

The determination and quantification of photosynthetic pigments by reverse phase high-performance liquid chromatography, thin-layer chromatography, and spectrophotometry.

Abstract: Chorophylls and carotenoids are functionally important pigment molecules in photosynthetic organisms. Methods for the determination of chlorophylls a and b, beta-carotene, neoxanthin, and the pigments that are involved in photoprotective cycles such as the xanthophylls are discussed. These cycles involve the reversible de-epoxidation of violaxanthin into antheraxanthin and zeaxanthin, as well as the reversible de-epoxidation of lutein-5,6-epoxide into lutein. This chapter describes pigment extraction procedures from higher plants and green algae. Methods for the determination and quantification using high-performance liquid chromatograpy (HPLC) are described as well as methods for the separation and purification of pigments for use as standards using thin-layer chromatography (TLC). In addition, several spectrophotometric methods for the quantification of chlorophylls a and b are described.