General Information for Practical Directions

A so-called standard (reference) solution must always be chromatographed at the same time it should contain from one to four of the principal components present in the solution under investigation. This procedure enables the positions of substance zones to be compared and also, if necessary, their sizes and colour reactions. Further, the positions 

The following is required of a standard solution for analysing a drug  

Although the technique in general, here TLC, is usually treated under general methods , the following data should be quoted in the drug monograph  

Note solvent and reagents selected for pharmacopoeia procedures should be, as far as possible, normally available in chemists shops or at least readily obtainable. 

This involves comparison of the chromatogram zones, if necessary of the spot areas and the behaviour during visualisation. The chromatogram of the solution under investigation is described with reference to that of the standard solution. 

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