Problems related to the optimum separation conditions in liquid adsorption chromatography

Summary Relationships derived from the thermodynamic formulation of TLC with a binary mobile phase are discussed. The adsorption equilibrium constant is determined from the linear form of a basic equation considering the adsorption process. This linear relationship is examined with help of TLC data obtained by using six different chromatographic systems. The adsorption equilibrium constant obtained from the TLC data is compared to the equilibrium constant determined from adsorption measurements. Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984     

Separation of aliphatic and aromatic amines by thin-layer chromatography using silica gel plates

Summary 28 different aromatic and aliphatic amines have been separated by TLC; 20 solvent systems were examined.     

Formation and migration of zones in overloaded preparative liquid-solid chromatography

Summary An equilibrium sandwich chamber for continuous thinlayer chromatography was used to study overloaded systems of the heptane + methylene chloride-silica type. Mixtures of two or three dyes were used as the model samples. Wide starting zones were formed using a glass distributor (frontal chromatography stage), then the movement of the zones was recorded during continuous elution. The effect of sample concentration and volume on the maximum separation yield was investigated. Band compression effects are illustrated for samples dissolved in solvents having a low eluent strength. Satisfactory analogy was found to separations in preparative column chromatography. Good separation yield was obtained for frontal + elution TLC: depending on the differences in the R_F values of the components, 6–16 mg samples were completely separated on 0.5×100×75 mm layers containing ca. 1 g of silica.Presented at the Eighth International Symposium on Liquid Chromatography, Baden-Baden, 3–7 May 1983.     

桂苓五味甘草煎膏剂质量标准研究

将五味子和甘草进行薄层色谱鉴别(TLC),并采用高效液相色谱法(HPLC)测定五味子醇甲的含量.结果表明:TLC法可明显鉴别甘草、五味子;五味子醇甲质量浓度在0.021～0.189 mg/mL范围内呈良好的线性关系,平均回收率为98.14％,相对标准偏差为2.01％.说明该实验的精密度、准确度、重现性、稳定性好,实验合理、可行、质量可控.     

光石韦药材中芒果苷的定性定量分析方法研究

为了研究光石韦药材中的芒果苷,建立定性定量分析方法,采用薄层色谱定性鉴别,高效液相色谱测定芒果苷含量。结果表明,薄层色谱鉴别方法的重现性好,芒果苷在0.0605～0.3632#g范围内呈良好线性关系（r=0.9996）,平均回收率为101.3%,RSD为2.13%（n=9）。方法简便、准确,专属性强,重现性和回收率好,可以为光石韦药材的质量标准制定提供分析方法和依据。     

Antimicrobial,DPPH scavenging and tyrosinase inhibitory activities of Thymus vulgaris,Helichrysum arenarium and Rosa damascena mill. ethanol extracts by using TLC bioautography and chemical screening methods

Antimicrobial, DPPH scavenging and tyrosinase inhibitory activities of Thymus vulgaris, Helichrysum arenarium and Rosa damascena Mill. ethanol extracts by using TLC bioautography and chemical screening methods. The ethanol extracts of Thymus vulgaris (Tv), Helichrysum arenarium (Ha) and Rosa damascena Mill. (Rm) (red) were screened for their antimicrobial, 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and tyrosinase inhibitory activities. The test microorganisms included bacteria of Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923). Thin Layer Chromatography (TLC) - bioautography, disk diffusion and well diffusion methods were used for the antimicrobial activity assays. Rosa damascena Mill. extract was effective against E. coli and all plant extracts showed antimicrobial activity against S. aureus. The phenolic acids in the structure of the extracts were also identified by LC-MS analysis. Human blood agar well diffusion method and TLC-DPPH assays were used to identify the hemolytic and antioxidant activity of plant extracts, respectively, along with 10 compounds including phenolic acids as a standard. Among these compounds, caffeic acid (Rf = 0.68) was detected in all extracts while vanillic acid (Rf = 0.75), and gallic acid (Rf = 0.51) was found in Tv extract. Kojic acid (Rf = 0.36), on the other hand, was detected in Rm extract as a tyrosinase inhibitor. All plant extracts presented tyrosinase inhibitory activities on TLC-bioautography assay.     

Forced flow,and physical field enhanced thin-layer chromatography

Planar chromatography was firstly introduced by Izmailow and Schreiber in 1938. Since then it has been used as a one of the basic techniques in liquid chromatography, but after introducing High Performance Liquid Chromatography in the 70’s of the past century by many investigators has been marginalized due to the worse separation capabilities and efficiency. The attempt of solving this problem was introducing forced flow planar techniques, and coupling it with other method of separation. In this article the ideas and history of Rotational Planar chromatography, Overpressured Layer Chromatography Planar Electrochromatography, and Thin Layer chromatography in Magnetic field have been presented. The short discussion on strong and weak sides of every presented technique and their further development possibilities was also included.     

Separation and identification of enzymatically prepared dephosphorylated products of myo‐inositolhexakisphosphate using LC‐MS

LC‐MS technique described here is a new way for the separation and direct determination of UV–Vis insensitive inositol phosphates (InsP₂‐InsP₆). This circumvents the need of radioisotopic labeling and post‐column derivatization techniques. The method involves separation of various enzymatically dephosphorylated derivatives of InsP₆ on C₁₈‐column using MeOH/H₂O (30:70 v/v) and their identification using electron spray ionization MS in positive ion mode (+pESI‐MS). The LC‐MS studies revealed that the purified phytase from Aspergillus niger van Teighem hydrolyzes InsP₆ in a sequential manner leading to InsP₂ (InsP₂·2Na, t_R 4.4–4.54 min, base peak m/z 382.9) as the end product.     

Direct enantiomeric TLC resolution of dl-penicillamine using (R)-mandelic acid and l-tartaric acid as chiral impregnating reagents and as chiral mobile phase additive

DL-Penicillamine has been resolved into its enantiomers by normal-phase TLC using L-tartaric acid as chiral impregnating reagent as well as chiral mobile phase additive, while (R)-mandelic acid has been found to be successful as a chiral impregnating reagent. The solvent system acetonitrile-methanol-water (5:1:1, v/v) was found to be successful when L-tartaric acid was used as impregnating agent while the solvent combination acetonitrile-methanol-(0.5% l-tartaric acid in water, pH 5)-glacial acetic acid (7:1:1.1:0.7, v/v) was successful as mobile phase as it contained L-tartaric acid as the chiral additive. (R)-mandelic acid was successful as chiral impregnating reagent with ethyl acetate-methanol-water (3:1:1, v/v), as the mobile phase. The effects of concentration of chiral selectors, temperature and pH were examined on enantiomeric resolution. The spots were detected with iodine vapors and the detection limits were found to be 0.12 microg for each enantiomer of penicillamine with L-tartaric acid, under both the conditions, and 0.11 microg with (R)-mandelic acid.