Advantages thin foil technique

Paper chromatography has been used successfully for many years and is still a useful tool despite the fact that thin-layer techniques, especially with readily available commercially prepared plastic or foil-backed plates, offer advantages of speed, resolution and easier handling. Larger volumes of sample can be applied to paper, permitting the subsequent elution of a particular amino... 

The use of other plastics tends to be related to specialised needs and whether their advantages justify the additional cost, e.g. Aclar (trade name) may cost twenty times more than PET but is the nearest approach to an inert plastic and is approximately ten times less permeable than Saran (PVdC—polyvinylidene chloride) which is widely used as a film coating. However foil, even when thin (0.006 mm and above) remains the best barrier material, with newer techniques of film metallisation, especially where two contact layers are used, coming a close second best. 

Pulse methods may be applied to both foil and bulk specimens provided that a suitable mathematical model is used in the data analysis. However, most applications of the potentiostatic pulse technique have involved just one surface of a metal specimen. The technique is suitable for bulk specimens since only a single surface need be exposed to the electrolyte, so it offers a practical advantage over permeation methods in that pinholes and sealing problems associated with thin membranes are avoided. Also, diffusion in such specimens can be treated in terms of a semi-infinite boundary condition, which is mathematically appealing. 

---