Quantitative Aspects Of PC And TLC:

As already emphasized, PC and TLC are primarily qualitative techniques used for identification of inorganic and organic compounds. However, both the techniques can also be used for quantitative analysis after taking proper care and suitable calibration so that reproducible and accurate results are obtained. Here, the most important aspect is that all the chromatographic conditions must be well standardized. The following precautions must be taken.

i) Standards and samples must be applied to the paper or plate in spots of similar size and at similar concentration using propipette.

ii) All the solvents must be of high purity. While using mixtures, these should be prepared carefully.

iii) Development chamber must be brought in equilibrium in the same manner. After the development of chromatogram, the spot area must be removed carefully by cutting the paper or scratching out from the plate and measured. Relative precision of these measurements is usually of the order of 5-10% but can be 1-2%. The main difficulties in quantitative measurements lie in defining the boundaries of spots and controlling chromogenic reactions in a reproducible manner.