Analysis methods thin-layer chromatography

Compared to other plasticizer analysis methods, thin layer chromatography is simple and quick. If used alone, it does not always lead to positive identification of every unknown plasticizing agent, but it does indicate the presence ol a plasticizer or a mixture of plasticizing substances. 

A series of tests carried out in Hungary analyzed 10 erection enhancement products, nine legal and one illegal. The analysis methods (thin-layer chromatography, gas chromatography and high-performance liquid chromatography) showed that six of the tested preparations contained synthetic phosphodiesterase inhibitors, one... 

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. 

The development of different methods of analysis in thin layer chromatography is a very important area of organic chemistry and biochemistry. Analysis of organic acids by thin layer chromatography is widely applied in different fields of environmental, pharmaceutical, industry, industrial foods, organic chemistry, cosmetics, clinical, and biochemical assays. 

Mycolic acids analysis by thin layer chromatography has been employed by several laboratories worldwide as a method for fast identification of Mycobacterium Mycobacterium tuberculosis strains identified by classical methods were confirmed by their mycolic acid content. 

Solute identification means qualitative analysis. Various methods are used today to identify a separated substance on a thin-layer chromatographic plate. Of all chromatographic methods, thin-layer chromatography (TLC) provides a unique simultaneous separation of up to 70 samples on the same plate therefore the reproducibility of the experimental conditions is not an issue because the experimental conditions are the same for all samples. This, together with the advantage of separating compounds with very different polarity and the possibility of using different detection methods for the same spot or for adjacent spots on the same plate, is the power of TLC. 

The merits of using SL and RTP as screening techniques for analysis of field samples were examined. These two methods were evaluated in conjunction with traditionally accepted methods thin layer chromatography (TLC), HPLC, and GC/MS (6). 

Sherma, J. Pesticide analysis by thin layer chromatography. In Analytical Methods for Pesticides and Plant Growth Regulators, Zweig, G., Sherma, J., Eds. Academic Press San Diego, CA, 1973 Vol. VII 3-87. 

This entry describes the classical and modem sample preparation methods that have been used prior to qualitative and quantitative analysis by thin-layer chromatography (TLC) and high-performance (HP) TLC. Extraction and cleanup methods that are covered include classical methods such as liquid-liquid extraction (LLE) and Soxhlet extraction, as well as modern methods such as solid-phase extraction (SPE), pressurized liquid extraction (PLE), and supercritical fluid extraction (SEE). Modern methods have not been as widely apphed in TLC as for other modes of chromatography, e.g., column high-performance liquid chromatography (HPLC). 

The total phosphoms content of the sample is determined by method AOCS Ja 5-55. Analysis of phosphoUpid in lecithin concentrates (AOCS Ja 7-86) is performed by fractionation with two-dimensional thin-layer chromatography (tic) followed by acid digestion and reaction with molybdate to measure total phosphorous for each fraction at 310 nm. It is a semiquantitative method for PC, PE, PI, PA, LPC, and LPE. Method AOCS Ja 7b-91 is for the direct deterrnination of single phosphoHpids PE, PA, PI, PC in lecithin by high performance Hquid chromatography (hplc). The method is appHcable to oil-containing lecithins, deoiled lecithins, lecithin fractions, but not appHcable to lyso-PC and lyso-PE. 

Thin-layer chromatography (TLC) is used both for characterization of alcohol sulfates and alcohol ether sulfates and for their analysis in mixtures. This technique, combined with the use of scanning densitometers, is a quantitative analytical method. TLC is preferred to HPLC in this case as anionic surfactants do not contain strong chromophores and the refractive index detector is of low sensitivity and not suitable for gradient elution. A recent development in HPLC detector technology, the evaporative light-scattering detector, will probably overcome these sensitivity problems. 

Marutoiu C, Sarbu C, Vlassa M, et al. 1986. A new separation and identification method of some organophosphorus pesticide by means of temperature programming gradient thin-layer chromatography. Analysis 14 95-98. 

Lipid Screening. The problems of lipid analysis in the newborn is difficult because of the fact that most methods for analysis for lipids require substantial amounts of serum, yet a total lipid determination is very important in various types of disease. This problem can be solved by thin-layer chromatography (59). Figure 38 shows a typical pattern obtained when an extract 7rom 10 microliters of serum is subjected to thin-layer chromatography. If these specimens are scanned, and an internal standard is run, one can obtain a rough approximation of the distribution of the various lipids in the serum. This is shown in Figure 39, in which a normal specimen is run in an adult. 

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