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Linné on line arrow Linnaeus and Pharmacy arrow Chemistry in nature arrow To Separate arrow The separation of Indian ink – a 10 minute laboratory experiment

The separation of Indian ink – a 10 minute laboratory experiment

Take a 10 x 10 cm thin layer chromatography plate (silica gel) and draw horizontal lines beside each other with one or several different felt pens about 1 cm from the plate’s lower edge. Then place the plate in a lidded container with less than 1 cm of acetone.

Three lines made by felt pens (blue, black and green) on a thin layer plate before and after chromotography.
Photo: Håkan Tunón.

A thin layer chromatography plate consists of a plate with a very thin layer of a powder. The tiny spaces between the various particles of powder cause a capillary action that slowly sucks up the solvent. When the acetone is being sucked up by the capillarity the colours will move at different rates and form different coloured bands. The ink in a pen consists not just of one but several different colours. The difference in the rate of progression depends on the water solubility of the various colour substances. If they are highly water soluble they will hardly progress at all whereas fat soluble substances move with the advancing edge of the acetone.