How to Analyze Food Colour Using Paper Chromatography

 How to Analyze Food Colour Using Paper Chromatography in the laboratory.

Paper chromatography identification of colour is one of the easiest way to identify food colours in the laboratory.

 IDENTIFICATION OF COLOUR BY PAPER CHROMATOGRAPHY 

PRINCIPLE: The movement of each colour in the mobile phase is different, thus there is comparison of the unknown colour with standard known colours, using differences in Retention Factor (RF). 

PROCEDURE: 

a) A paper chromatograph of about 15cm ×10cm

b) A line is drawn with pencil, parallel to the bottom of a piece of chromatography paper, about 2cm away from the origin,

c) Using a pencil drawn out capillary spot for each colour; a concentrated solution of the unknown colour is spotted on the line together with series of spots (2-3cm apart) of aqueous solutions of similar standard colours.

d) The paper is rolled into a cylinder, clipped and placed in 1cm layer of mobile phase ( 1% ammonia and 99% disilled water) in a 500ml beaker and covered. After the solvent front has moved 10-12cm remove the paper, the spots are left to dry and then compared.

Solvent front of sample equivalent to that of standard colour contains the same colour. The standard to which the sample colour tested on the chromatogram has equal solvent front is the colour in the food sample.

The following colours are permitted in food: Yellow Tartrazine, Sunset Yellow, Red Carmosine, Red Amarane, Caramel, Red Amaranth, Erythrosine, Brilliant Blue.