HPTLC chromatography

Glycosphingolipids with similar structures are found in Crithidia spp, which are considered to be lower trypanosomatids as their habitat is in invertebrate and since they do not have a cycle involving vertebrates (39). Neutral glycosphingolipids were isolated and characterized in Crithidia luciliae, C.oncopelti and C.guilhermei (40). The major glycolipids of the three species of Crithidia detected by HPTLC chromatography contain... 

Among the verity of PP those containing flavonoids and lipophilic plant ingredients were selected as widely used and rather labile. Sample preparation varied to accommodate certain product type. Samples were chromatographied on Sorbfill HPTLC plates in saturated twin trough chamber. 

Commercially available pre-coated plates with a variety of adsorbents are generally very good for quantitative work because they are of a standard quality. Plates of a standardised silica gel 60 (as medium porosity silica gel with a mean porosity of 6mm) released by Merck have a specific surface of 500 m /g and a specific pore volume of 0.75 mL/g. They are so efficient that they have been called high performance thin layer chromatography (HPTLC) plates (Ropphahn and Halpap J Chromatogr 112 81 1975). In another variant of thin layer chromatography the... 

As a result of these merits thin layer chromatography finds application all over the world. The frequency of its application is documented in Figure 3. This CA search only includes those publications where TLC/HPTLC are included as key words. The actual application of the method is very much more frequent. The method is employed as a matter of course in many areas of quality control and routine monitoring of product purity. This was also true in the 1970s when the rapid development of high performance liquid chromatography (HPLG) led to a... 

Hezel, U. B., in Zlatkis, A., Kaiser, R. E. HPTLC - High Performance Thin Layer Chromatography. J. Chromatogr. Library, Vol. 9. Elsevier, Amsterdam 1977. 

On the basis of theory and experimental observations it can be predicted that a zone capacity of ca. 1500 could be achieved by 2-D multiple development. Because the same result can be achieved by application of 2-D forced-flow development on HPTLC plates, it can be stated that the combination of stationary phases, FFPC and "D offers a fruitful future in modem, instmmental planar chromatography. 

HIGH PERFORMANCE THIN-LAYER CHROMATOGRAPHY (HPTLC)... 

Recent developments in the practice of thin-layer chromatography have resulted in a breakthrough in performance which has led to the expression high performance thin-layer chromatography . These developments have not been the result of any specific advance in instrumentation (as with HPLC), but rather the culmination of improvements in the various operations involved in TLC. The three chief features of HPTLC are summarised below, but for a comprehensive account of the subject the reader is recommended to consult a more specialised text.59... 

A Zlatkis and R E Kaiser (Eds), HPTLC High Performance Thin-Layer Chromatography, Elsevier, Amsterdam, 1977... 

HPTLC, high performance thin layer chromatography. 

This volume is the second of a series of practice-orientated TLC/HPTLC books published in excellent quality by VCH Publishers. As in the first volume, a series of reagents and detection methods have been reviewed with the intention of helping the practical analyst increase the detection specificity of routine samples separated by thin-layer chromatography. 

Fig. 12 DC-Mat (Baron, Desaga), opened. The flap bearing the HPTLC plate is folded upwards during chromatography, so that the deveiopment can take place in the dark.

Thin-layer chromatography has the great advantage that the result of the separation is stored — usually invisibly — on the TLC/HPTLC plate as on a diskette. In such cases it needs developing or detecting, rather like an exposed film. This can now be done online or off-line so that the analyst can decide which method to use to detect the separated substances. 

Fig. 1 Fields of application of thin-layer chromatography (TLC/HPTLC) during the pei 1988-1991.

The reason for this lies not least in the increasing instrumentalization and delibei automation of all those processes which were earlier particularly subject to eri (Fig. 2). Modem high performance thin-layer chromatography (HPTLC) is no Ion inferior to other liquid chromatographic techniques with respect to precision and s sitivity (Fig. 3) [6]. 

Spectrophotometric resolution for the discrimination of individual colorant molecules found in mixtures is lower than that of chromatographic techniques such as TLC or HPTLC and even low-cost paper chromatography. More expensive but more accurate determinations may be made by RP-HPLC, IP-HPLC with UV-Vis, and diode array detection. ... 

Morita et al. [69] optimized the mobile phase composition using the PRISMA model for rapid and economic determination of synthetic red pigments in cosmetics and medicines. The PRISMA model has been effective in combination with a super modihed simplex method for fadhtating optimization of the mobile phase in high performance thin layer chromatography (HPTLC). 

The Window diagram method for the optimization of separation was developed by Laub and Purnell [73], and it has been used both for gas chromatography and HPLC. Recently it is applied in TLC and HPTLC [19,74—76]. 

FIGURE 6.19 Circular chromatography of dyes on precoated silica gel high-performance TLC plate lipophilic dyes, mobile phase hexane-chloroform-NH3, 70 30. (From Ripphahn, J. and Halpaap, H., HPTLC High Performance Thin Layer Chromatography, Zlatkis, A. and Kaiser, R. E., Eds., Elsevier, Amsterdam, 1977, pp. 189-221. With permission.)... 

PLC is used for separations of 2 to 5 mg of sample on thin-layer chromatography (TLC) plates (0.25-nun layer thickness) or high-performance TLC (HPTLC) plates (0.1-mm thickness). In these instances, the method is termed micropreparative TLC. The isolation of one to five compounds in amounts ranging from 5 to 1000 mg is carried out on thicker layers. PLC is performed for isolation of compounds to be used in other tasks, i.e., further identification by various analytical methods, such as ultraviolet (UV) solution spectrometry [1] or gas chromatography/mass spectrometry (GC/MS) [2], obtaining analytical standards, or investigations of chemical or biological properties [3]. 

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