Quantitative thin-layer chromatography introduction

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. 

The determination of PG is a commonly used qualitative method used to assess FLM in the United States. Measurement of PG was classically performed by thin-layer chromatography. It could be performed alone or in combination with other amniotic fluid phospholipids. The later test was loiown as a lung profile since its introduction in the early 1970s. Although thin-layer chromatography is still offered by some reference and hospital laboratories, most hospital laboratories use a rapid slide method for qualitative PG detection. Several enzyme-based tests for quantitative PG have also been published, but none is widely... 

Thin-layer chromatography (TLC) is a very old method of analysis that has been well proven in practice. For more than thirty years, it has occupied a prominent position, especially in qualitative investigations. With the development of modern precoated layers and the introduction of partially or completely automated equipment for the various stages of operation of TLC, not only are highly accurate quantitative determinations now possible, but also the requirement that the work should comply with the GMP/GLP guidelines can be fulfilled. 

Paper chromatography may be used as one step for separation and/or isolation of anthocyanins from complex samples. Thin-layer chromatography, performed on cellulose or silica gel plates, was in the first period of use a convenient extension of paper chromatography. The introduction of new stationary phases and the development of instrumentation offering the possibility of quantitative analysis provided new possibilities for method developments. The advantages of TLC are the simplicity in terms of instrumentation, sample preparation and data evaluation. 

The introduction of any new analytical technique seems to inspire its indiscriminate application, without use of proper precautions, to a variety of problems, many of which could be solved more quickly by other methods. It should be emphasized that gas-liquid chromatography is not a panacea for all problems in the analysis of carbohydrate derivatives. Fast, efficient resolution of any given mixture of derivatives requires judicious selection from among the methods of countercurrent partition, liquid-liquid chromatography on columns or paper, adsorption chromatography on columns or thin layers, electrophoresis, and gas-liquid chromatography. The last method is, under the appropriate conditions, a powerful addition to the list because of its high efficiency and rapid operation, and the reliability of both the qualitative and the quantitative results. 

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