Paper Chromatography provides a simple and cost effective means for separation of components of mixtures. You would have seen the separation of different coloured compounds using the simple paper chromatographic separation technique in your school laboratory. The technique was simple to understand and did not require any expensive equipment. It provided you a visual understanding of the concepts of separation science. In your college time you would also have come across thin layer chromatography separations of compounds which even after separation may or may not be identifiable by the eye without treatment of the separation plate.
Thin layer chromatography offers several benefits over the paper chromatographic separations some of which are highlighted in this article.
The biggest advantage offered to the chromatographer is time-saving. Paper chromatography can take several hours to develop the plate whereas development in thin layer chromatography can be completed in much shorter time (about half an hour or so)
Paper chromatography has not seen much automation over the years but thin layer chromatography instruments available have automation capabilities which include autosampler, constant volume sample dispenser, documentation and camera for retaining pictorial record of separations
The cellulose paper support in paper chromatography is flexible whereas the adsorbent in TLC is coated onto a rigid metal, glass or plastic plate. This contributes to reproducibility of spots and faster development. Due to support rigidity there is less diffusion and as a result well-defined spots are formed.
Choice of support
TLC presents a vast choice of support adsorbent phases including liquid coated adsorbents which can include fluorescence inducers as well. On the other hand choice of papers in paper chromatography is very much limited.
Development chamber design
It is not necessary to suspend the plate as required in paper chromatography from a rod on top of the development chamber. It can be simply placed in a slanting position with its bottom edge resting on the chamber base.
The quantity of sample applied is small( in microliters) and can be reproducibly applied with the help of automated sample dispensers
Choice of spray reagents
Corrosive spray reagents can char the filter paper and can even deteriorate the sample spots. Coated plates used in thin layer chromatography can withstand corrosive spray reagents to a greater extent
Thin-layer chromatography plates can be heated if required for spot development. Paper chromatography sheets cannot withstand heating beyond a point.
In summary thin layer chromatography offers several advantages to the separation scientist only for a small additional cost of the thin layer coated plates.