Thin layer chromatography separation

Sz. Nyiredi, C.A.J. Erdelmeier, B. Meier, O. Sticher, The PRISMA mobile phase optimization in thin-layer chromatography Separation of natural compounds, Planta Medica 3 (1985) 241-246. 

Exercises in thin-layer chromatography. Separation of amino acids. Prepare solutions of DL-alanine, L-leucine and L-lysine hydrochloride by dissolving 5 mg of each separately in 0.33 ml of distilled water, measured with a graduated 1 ml pipette (leucine may require warming to effect solution). Mix one drop of each solution to provide a mixture of the three amino acids and dilute the remainder of each solution to 1 ml to give solutions of the respective amino acids. The latter will contain about 5 pg of each amino acid per pi. Apply approximately 0.5 pi of each of the solutions to a Silica Gel G plate and allow to dry in the air (i.e. until the spots are no longer visible). 

The 2-D TLC was successfully applied to the separation of amino acids as early as the beginning of thin-layer chromatography. Separation efficiency is, by far, best with chloroform-methanol-17% ammonium hydroxide (40 40 20, v/v), n-butanol-glacial acetic acid-water (80 20 20, v/v) in combination with phenol-water (75 25, g/g). A novel 2-D TLC method has been elaborated and found suitable for the chromatographic identification of 52 amino acids. This method is based on three 2-D TLC developments on cellulose (CMN 300 50 p) using the same solvent system 1 for the first dimension and three different systems (11-IV) of suitable properties for the second dimension. System 1 n-butanol-acetone -diethylamine-water (10 10 2 5, v/v) system 11 2-propanol-formic acid-water (40 2 10, v/v) system 111 iec-butanol-methyl ethyl ketone-dicyclohexylamine-water (10 10 2 5, v/v) and system IV phenol-water (75 25, g/g) (h- 7.5 mg Na-cyanide) with 3% ammonia. With this technique, all amino acids can be differentiated and characterized by their fixed positions and also by some color reactions. Moreover, the relative merits of cellulose and silica gel are discussed in relation to separation efficiency, reproducibility, and detection sensitivity. Two-dimensional TLC separation of a performic acid oxidized mixture of 20 protein amino acids plus p-alanine and y-amino-n-butyric acid was performed in the first direction with chloroform-methanol-ammonia (17%) (40 40 20, v/v) and in the second direction with phenol-water (75 25, g/g). Detection was performed via ninhydrin reagent spray. 

Sometimes, the gas chromatographic retention times of two or more materials are so close that an identification is difficult, even if two different columns have been used. A thin layer chromatography separation (Chapter 22) then can be used, but this generally requires a lengthy cleanup and concentration because of the small (nanogram) samples involved. A much quicker method is the use of P-values. This method is based on the distribution of the pesticides between two immiscible phases. 

EXPERIMENT 31 THIN-LAYER CHROMATOGRAPHY SEPARATION OF AMINO ACIDS... 

The best yields were obtained with (Me3SiS)2R and R = C3H6 or C4H8. In the case of R = C2H4, oligomeric compounds were formed. The reaction with SCI2 is carried out in THF followed by evaporation of the solvent and of MesSiCl and preparative TLC (Thin-layer Chromatography) separation with hexane as an eluent. 

In the iodination of molecules with low MW, Na I usually serves as the source of and chloramine T as the oxidizer (molar ration of the three reactants about 1 1 1). A slightly basic pH of the reaction mixture favors the monoiodination. With compounds that are sensitive to water (e.g., N-succinimidyl derivatives), the iodination reaction is carried out in organic solvents (e.g., acetone, acetonitrile). The iodination efficiency depends on the solvent being used. HPLC or thin-layer chromatography separates free iodine, iodized molecule, and noniodized molecule. 

The biological activity of total, polar and neutral lipids, as well as purified fractions of each lipid class after thin layer chromatography separations (Nasopoulou et al., 2007) was studied against washed rabbit platelets according to the method of Demopoulos et al. (1979)... 

Thin-layer chromatography (separations) can be made using either plates prepared in the laboratory or ready-prepared TLC plates. Plates with... 

D.W. Armstrong and M. McNeely,fAe of Micelles in the Thin Layer Chromatography Separation of Polynuclear Aromatic Compouruk and Amino-Acids, Anal. Lett., 12 1285 (1979). 

Thin-Layer Chromatography separation and determination of purine and pyrimi-... 

Thin-layer chromatography Separation of dyes Comparison of dye components from known and questioned fibers... 

Reaction Procedure (Scheme 2.161) A mixture of o-bromobenzaldehyde (2 mmol), 1,3-dicarbonyl compound (2 mmol), PdCl2(PPh3)2 (0.02 mmol), PPha (0.08 mmol), and sodium acetate (2 mmol) in DMF was placed in a pressure vessel. After the system was flushed and then pressurized with carbon monoxide (20 atm), the mixture was stirred at 80 °C for 8 h. The reaction mixture was filtered through a short column (silica gel) and evaporated under reduced pressure. Preparative thin layer chromatography separation using ethyl acetate-hexane (10 3) as an eluent gives 3-all lphthalides. 

Geiss, F., and Schlitt, H, (1968). A new and versatile thin layer chromatography separation system (KS-Vario-Chamber). Chromatographia I 392-402. 

The results of a thin-layer chromatography separation on silica gel are shown below. 

L. Vrabski, S. Markov, J. Jakovlijevic, and Z, Lepojevic, Improved thin-layer chromatography separation of carbohydrates in wort and beer, Biotechnol.-Tech. 6 413-416 (1992). 

Due to the small beam diameter ( 1 mm to 1 /xm) of the laser excitation source, only small samples are required (<1 /xg). This allows the technique to be easily coupled to gas, liquid, and thin-layer chromatography separation techniques. Moreover, this allows for high spatial resolution of samples. 

Sturm, P. A., R. M. Parkhurst, and W. A. Skinner. 1966. Qualitative determination of individual tocopherols by thin layer chromatography separation and spectrophotometry. Anal. Chem. 38 1244-1247. 

Bhushan, R. and Gupta, D., Thin-layer chromatography separation of enantiomers of verapamil using macrocyclic antibiotic as chiral selector, Biomed. Chromatogr., 19, 474-478, 2005. 

De Vault, GL. and Sepaniak, M.J., Two-dimensional capillary eleclrophoresis-thin layer chromatography separations of amino acid enantiomers using electrofilament transfer, J. Micro. Sep., 12 419, 2000. 

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