Paper Chromatography started to interess me in 1997 - 1998, when I finished the Project about Metal Cation Identification, and was learning Chromatography during the MLS course at the Institute of Health Care. I was becoming curious about what dyes are used in comemrcial pens, ball points, markers and various writing instruments. Also I was encoaraged by the fact that the procedure is very simple and straight forward, and I could obtain quite some small quantities of solvents from the hospital labs such as Ethanol, Methanol, Chloroform etc. Hence, I started to device a standard method to perform my chromatography experiments. I tried various approaches until finally a good method in my home-lab was produced.
In this Chromatography section you can read the principle and history of paper chromatograph, my method for achieving good results with paper chromatography, inks I tested, and the particular dyes / pigments isolated, with their RF values for several solvents
PRINCIPLE of CHROMATOGRAPHY
In analytical chemistry, technique for separating dissolved chemical substances by taking advantage of their different rates of migration across sheets of paper. It is an inexpensive but powerful analytical tool that requires very small quantities of material.
The method consists of applying the test solution or sample as a spot near one corner of a sheet of filter paper. The paper is initially impregnated with some suitable solvent to create a stationary liquid phase. An edge of the paper close to the spot is then immersed in another solvent in which the components of the mixture are soluble in varying degrees. The solvent penetrates the paper by capillary action and, in passing over the sample spot, carries along with it the various components of the sample.
The components move with the flowing solvent at velocities that are dependent on their solubilities in the stationary and flowing solvents. Separation of the components is brought about if there are differences in their relative solubilities in the two solvents.
Before the flowing solvent reaches the farther edge of the paper, both solvents are evaporated, and the location of the separated components is identified, usually by application of reagents that form coloured compounds with the separated substances. The separated components appear as individual spots on the path of the solvent. If the solvent flowing in one direction is not able to separate all the components satisfactorily, the paper may be turned 90 and the process repeated using another solvent. Paper chromatography has become standard practice for the separation of complex mixtures of amino acids, peptides, carbohydrates, steroids, purines, and a long list of simple organic compounds. Inorganic ions can also readily be separated on paper.
HISTORY of CHROMATOGRAPHY
Click here to read a the document about the history of chromatography.
METHODOLOGY and STANDARD PROCEDURE
Click here to read a detailed document about the a standard procedure to perform the paper chromatography tests.
PROPERTIES OF SOLVENTS USED
Click Here to read about various Chromatography tests using a standard ink material on different solvents of which some are also tested at different concentrations. The efficiency and solvent characteristics is accounted for.
Here you will find paper chromatography tests on different types of samples of ink, dyes, etc. applying different solvents and solvent mixtures. Click on the sample names below or enter the main sample menu
Here you will find a brief account on the dyes isolated by chromatography from tested samples. This account includes physical characteristics, few chemical tests and attempts to try and identify the actual dye. Unless the dye is identified a temporary in-house nick name is give for the isolated dyes. Click below on the list of dyes that have been isolated so far.
Click here to read about various RF Value results obtained from different dyes with specific solvents and solvent concentrations. Th Rf value is a specific value for the dye and solvent used, hence it is a good tool for identification where an unknown Rf result is compared with Rf values of known dyes.
Chromatography Section Links :
[ Main Page ] -
[ Methodology ] -
[ Solvents Used ] -
[ Rf Values ] -
[ Ink Sample Analysis ] -
[ Extracted Dyes ] -
[ History ]
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