The Saturated N-Chamber

A particularly impressive example of an improved result after development in a saturated N-chamber is shown by the chromatogram of the separation of spironolactone and furosemide on normal silica gel 60, where without chamber saturation the spironolactone is in the front and the furosemide is slightly below this (Fig. 60a,b). However, in this example the development is performed with a CHC-containing solvent system, and an alternative system for separating these two substances is therefore given in Table 15. Other information on the conditions is also given. 

The lid of the TLC chamber must on no accoimt be opened during the chromatographic development process It is therefore a good idea to leave a viewing slit in the CS filter paper lining to check the height of the solvent system. 

To produce saturation of the chamber, circular filter papers must never be used, as these would not take up solvent over the whole width of the chamber. 

To line the developing chambers for this purpose, filter papers with good absorption properties for the solvent system should always be used, although if the filter paper is too thick it can become separated from the chamber wall, so that the TLC plate is no longer firmly supported. Suitable filter paper is marketed in sheet form by Schleicher Schtlll (Article No. 604, 58 x 58 cm). 

For qualitative work, the sheets of filter paper should be cut into pieces of size ca. 19.6 X 19.6 cm. To do this, several sheets are stacked together and folded twice, each fold being 19.6 cm from the edge. The paper is then cut twice with a guillotine to produce 19.6 x 58 cm sheets, each folded twice. These are cut along the folds to give 19.6 X 19.6 cm sheets, which can be conveniently stored at the TLC workplace and can be cut up as required to obtain smaller formats. 

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