Thin-layer chromatography sample application

The procedure of paper and thin-layer chromatography. A Application of the sample. B Setting plate in solvent chamber. C Movement of solvent by capillary action. D Detection of separated components and calculation of Rf. 

It is ommon practice in thin-layer chromatography, after application of a sample to a given plate, to develop the plate two or more times with drying of the plate between developments. This general technique will be referred to as multiple development. Three types of multiple development... 

Creatinine. Electrophoresis Principles Isoelectric Focusing. Enzymes Enzymes In Physiological Samples Industrial Products and Processes Enzyme Assays. Forensic Sciences Alcohol In Body Fluids DNA Profiling Systematic Drug Identification Thin-Layer Chromatography. Immunoassays Applications Forensic. Microscopy Applications Forensic. Nucleic Acids Electrochemical Methods. Polymerase Chain Reaction. Spectrophotometry Oven/lew Biochemical Applications. 

Although the interest in, and application of layer chromatography has historically resulted from the development of PC, it was soon replaced by thin-layer chromatography (TLC). In PC, only one stationary phase matrix is available (cellulose), at variance to TLC (silica, polyamide, ion-exchange resins, cellulose). Using a silica-gel plate, separation of a sample can be accomplished in approximately 1 h as compared with many hours on paper. The plate size is much smaller than the necessary paper size. Also, more samples can be spotted... 

Thin-layer chromatography (TLC) is one of the most popular and widely used separation techniques because it is easy to use and offers adequate sensitivity and speed of separations. Furthermore, multiple samples can be run simultaneously. It can be used for separation, isolation, identification, and quantification of components in a sample. The equipment used for performance of TLC, including applications of TLC in drug discovery process, is covered in Chapter 13. This technique has been successfully used in biochemical, environmental, food, pharmacological, and toxicological analyses. 

M. Mecozzi and Zs. Papai, Application of curve fitting thin-layer chromatography-flame ionization detection analysis of the carbohydrate fraction in marine mucilage and marine snow samples from Italian seas. J. Chromatogr. Sci. 42 (2004) 268-274. 

Thin-layer chromatography (TLC), sometimes also called planar chromatography, employ a stationary phase immobilized on a glass or plastic plate and an organic mobile phase. It is a rather old technique whose application in residue analysis has been limited in the past by poor chromatographic resolution, inadequate selectivity, and insufficient sensitivity (49). This was due to inherent problems in the quality of the available stationary phase materials and in the uniformity of the layers prepared. Today, the availability of affordable, precoated plates with acceptable performance and consistency has led to the general acceptance of TLC as an efficient procedure for residue analysis (50). The method is used preferentially when analysts must process large numbers of samples in a short period of time (51). 

Taylor and co-workers further demonstrated the value of open-access LC/MS systems for generating a widened scope of pharmaceutical analysis applications, including (1) characterization of synthetic intermediates and target compounds (2) reaction monitoring (3) reaction optimization (4) analysis of preparative HPLC fractions and (5) analysis of thin layer chromatography (TLC) plate spots. The availability of these methods led to the increased use of LC/MS for structural analysis. The short analysis time and reliable structure confirmation resulted in the use of LC/MS as a first choice for structure characterization for synthetic chemistry applications, as well as an expanded, and perhaps, integrated role of sample generator and analyst. 

Thin-layer chromatography (TLC) is another liquid-liquid partition technique applicable to polysaccharides, but in two dimensions. In TLC, the M cutoff boundaries between separated molecules are sharpened, because diffusion is minimized or eliminated in favor of capillary transport. The sample capacity of a TLC plate is in microliters. Resolution is enhanced further at high solvent pressure (Rombouts and Thibault, 1986). 

Thin-layer chromatography is very widely used, mainly for qualitative purposes almost any mixture can be at least partially resolved. Inorganic applications, such as the separation of metals in alloys, soil and geological samples, and polar organic systems, such as mixtures of amino acids or... 

The separation and identification of natural dyes from wool fibers using reverse-phase high-performance liquid chromotog-raphy (HPLC) were performed on a C-18 column. Two isocratic four-solvent systems were developed on the basis of the Snyder solvent-selectivity triangle concept (1) 10% acetonitrile, 4% alcohol, and 2% tetrahydrofuran in 0.01 M acetic acid and (2)7% acetonitrile, 8% alcohol, and 5% tetrahydrofuran in 0.01 M acetic acid. Samples were also eluted in 30% acetonitrile. Spot tests and thin-layer chromatography were performed on all samples to confirm HPLC results. The systems also were found to be potentially useful in the identification of early synthetic dyes. A system of sample preparation that minimizes the reaction of samples was discussed. The application of this HPLC separation technique to samples from 20th century Caucasian rugs and American samples unearthed from the foundation of Mission San Jose was examined. 

Thin-layer chromatography will continue to play a basic role to complete the separation possibilities by chromatographic methods for the routine analysis of a large number of samples, or to analyse samples in cases where HPLC has difficulties. Therefore, TLC procedures are important. A number of further improvements can be expected in the basic steps of TLC analysis such as sample application, separation of the sample components, and detection of the more or less separated components ... 

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