Quantitative analysis thin-layer chromatography

Sethi, ED. HPTLC, High Performance Thin-Layer Chromatography, Quantitative Analysis of Pharmaceutical Formulations, CBS Publisher Distributors, New Dehli (India) 1996, ISBN... 

Analysis. Dilute aqueous solutions of hydroxyhydroquiaone turn blue-green temporarily when mixed with ferric chloride. The solutions darken upon addition of small amounts, and turn red with additions of larger amounts of sodium carbonate. Derivatives used for identification are the picrate, which forms orange-red needles (mp of 96°C), and the triacetate (mp 96—97°C). Thin-layer chromatography and Hquid chromatography are well suited for the quahtative and quantitative estimation of hydroxyhydroquiaone (93,94). 

The multiplicity of responses makes thin-layer chromatography not particularly suited for pyrethrum analysis, either qualitative or quantitative. It did confirm, however, that the crude oleoresin contains several pyrethroid compounds in substantial quantity, as previously shown by gas chromatography work. 

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. 

The first part of the book consists of a detailed treatment of the fundamentals of thin-layer chromatography, and of measurement techniques and apparatus for the qualitative and quantitative evaluation of thin-layer chromatograms. In situ prechromatographic derivatization techniques used to improve the selectivity of the separation, to increase the sensitivity of detection, and to enhance the precision of the subsequent quantitative analysis are summarized in numerous tables. 

Simultaneous evolution of chromatography, as a method of analysis and separation, enables the confirmation and development of chemotaxonomic investigations of new plant species, as well as the accomplishment of quality and quantitative determinations. Thin-layer chromatography (TLC) especially proved to be very useful for analysis and isolation of small amounts of some compounds. The most significant and advantageous points of the TLC technique are its speed, cheapness, and capacity to carry out the analysis of several solutes simultaneously its continuous development under equilibrated conditions its gradient and multiple development and its ability to scale up the separation process. 

The latest innovation is the introduction of ultra-thin silica layers. These layers are only 10 xm thick (compared to 200-250 pm in conventional plates) and are not based on granular adsorbents but consist of monolithic silica. Ultra-thin layer chromatography (UTLC) plates offer a unique combination of short migration distances, fast development times and extremely low solvent consumption. The absence of silica particles allows UTLC silica gel layers to be manufactured without any sort of binders, that are normally needed to stabilise silica particles at the glass support surface. UTLC plates will significantly reduce analysis time, solvent consumption and increase sensitivity in both qualitative and quantitative applications (Table 4.35). Miniaturised planar chromatography will rival other microanalytical techniques. 

Thin-layer chromatography (TLC)2 has become a valuable tool for the qualitative and semi-quantitative analysis of various organic and mor-... 

The development of the open-column methods, ie paper chromatography (in the 1940 s) and thin-layer chromatography (in the 1950 s) greatly improved the speed and resolution of lc, but there were still serious limitations compared to modern lc methods, in that analysis times were long, resolution was poor and quantitative analysis, preparative separations and automation were difficult. 

The identification and quantitation of the individual amino acids in a mixture is often required in metabolic studies and investigations of protein structure. The use of thin-layer chromatography or electrophoresis may be adequate to indicate the relative amounts and number of different amino acids in a sample but the use of gas-liquid chromatography or an amino acid analyser is essential for quantitative analysis. 

The toxins are easily detected, after separation of the compounds from plasma and renal tissue on silica thin layers, by their fluorescence in UV light orellanine is visible as navy blue, orellinine as dark blue, and orelline as light blue (Horn et al., 1997). Beside thin-layer chromatography (TLQ, use of HPLC for the analysis of orellanine, e.g., in mushroom extracts, has also been reported. Quantitative analysis of orellanine in plasma samples, or in (rat) urine samples, was performed by extraction of orellanine on XAD-4 resin, two-dimensional TLC on cellulose, and spectrophotometric evaluation of the orelline produced on the TLC plates after UV-induced decomposition of the orellanine. 

Analysis of On-Site Wastewaters for Pesticides by Thin-Layer Chromatography. A field method to identify qualitatively and semi-quantitatively the pesticide constituents of a pesticide-laden wastewater was developed. The field method was developed using thin-layer chromatography (TLC). TLC gives a presumptive test for the presence of specific pesticides and within 30 minutes an estimate of their concentrations. TLC may also reveal the presence of unknown substances. The field application of thin-layer chromatography requires a skilled chemist, but no expensive equipment. The following protocol describes the on-site use of TLC. 

Thin-Layer Chromatography. Thin-layer chromatography was used for many of the compounds which are of interest for either qualitative or quantative analysis. These techniques were used primarily as screening methods to supplement other analytical methods. For some brominated compounds such as TRIS, the detection system reported by Hahn (9) was applicable. This method is based upon the reaction of fluorescein with elemental bromine released through peroxide oxidation. An evaluation in our laboratory of this detection system indicated that semi-quantitative results... 

Several technology leaps have taken place in separation sciences during the lifetime of the pharmaceutical industry. The development of chromatography at the end of the nineteenth century was the first of these revolutions and its transformation into thin-layer chromatography (TLC) provided the mainstay for quantitative analysis well into the second half of the twentieth century. With the development of gas chromatography (GC) after World War II and high-performance liquid chromatography (HPLC) two decades later, the age of fully instrumented separation science had arrived. 

Frangopol and Morariu have edited a seminar on procaine and related drugs, methods of analysis, and effects on cell membranes [29]. Items covered include studies on Romanian drugs by mass spectrometry and gas chromatography-mass spectrometry, quantitative and qualitative determination of procaine in biological samples, separation and quantitative thin layer chromatography determination of procaine... 

In earlier times, thin-layer chromatography (TLC), polyamide chromatography, and paper electrophoresis were the major separation techniques for phenolics. Of these methods, TLC is still the workhorse of flavonoid analysis. It is used as a rapid, simple, and versatile method for following polyphenolics in plant extracts and in fractionation work. However, the majority of published work now refers to qualitative and quantitative applications of high-performance liquid chromatography (HPLC) for analysis. Llavonoids can be separated. 

It has been demonstrated that ILMs are suitable for qualitative and quantitative analyses of low-molecular weight compounds of biological interest, for example, carbohydrates, vitamins and amino acids [38], and glycolipids [40]. ILMs were further used for fhe direct analysis of alkaloids, anesthetics and antibiotics, separated by thin-layer chromatography (TLC) [46]. For this purpose, the ILM was spotted onto the fractions on the TLC-plates and the complete plate was measured in MALDI MS without the need for additional pretreatment of the TLC-samples. The mass deviation inherently caused by the inhomogeneous surface of fhe TLC-plafe was balanced by using the... 

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