Paper chromatography

Paper chromatography is an analytical technique for separating and identifying mixtures that are or can be colored, especially pigments. This can also be used in secondary or primary schools in ink experiments. This method has been largely replaced by thin layer chromatography, however it is still a powerful teaching tool. Two-way paper chromatography, also called two-dimensional chromatography, involves using two solvents and rotating the paper 90° in between. This is useful for separating complex mixtures of similar compounds, for example, amino acids.

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Analysis

After development, the spots corresponding to different compounds may be located by their color, ultraviolet light, ninhydrin (Triketohydrindane hydrate) or by treatment with iodine vapors. The final chromatogram can be compared with other known mixture chromatograms to identify sample mixes using the R_f value in an experiment.