Thin Layer Chromatography Report

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Register to read the introduction… Samples are applied to a stationary phase and then a mobile phase is passed through it, food dyes can be separated and identified by (TLC). In (TLC) the stationary phase provides the surface for molecules to absorb and the moving phase consists of a solvent which travels up the chromatogram by capillary action across the stationary phase. The solvent may be either a polar or non-polar solvent, depending on the basis of the separation. The stationary phase is a substance called silica gel which is a form of silicon dioxide (silica). The silicon atoms are connected by oxygen atoms in a giant covalent structure. However, at the surface of the silica gel, the silicon atoms are attached to (-OH) groups. Therefore, at the surface of the silica gel there is (Si-O-H) bonds instead of (Si-O-Si) bonds. The surface of the silica gel is very polar and because of the (-OH) groups, it can form hydrogen bonds with suitable compounds around it as well as Van Der Waals forces and dipole-dipole attractions. The silica gel acts as an adsorbent, which is a solid that is capable of attracting and binding the components in a mixture[ …show more content…
The separation is based on polarity, most dyes are all polar, well at least all FD&C approved dyes are, and soluble in water. The food dyes that are used in foods are made of soluble organic compounds and contain sulfonic acids. Sulfonic acids are relatively strong acids. When they are present in food, FD&C dyes will be ionized and carry negative charges. This ionic character makes them water-soluble and provides a means for separating them from other components in the …show more content…
Data Processing:-

Rf= Distance from the start to the centre of the spot
Distance from start to solvent front

Using the rubbing(isopropyl) alcohol solution:

Candy Colour Colour separated into: Average Distance from base line to centre of spot/cm
Rf values

M&M’s Brown Orange 4.8 0.28 Purple 6.3 0.37 Blue 8.4 0.49
Skittles Green Blue 8.7 0.51 Yellow 12.5 0.74
Gems Orange Orange 13.3 0.78

Using the Butanol-methyl ethyl ketone-water-ammonia solution:

Candy Colour Colours separated into: Average Distance from base line to centre of spot/cm
Rf values

M&M’s Brown Orange 0.5 0.03 Purple 1.4 0.08 Blue 3.6 0.21
Skittles Green Blue 3.5 0.21 Yellow 4.3 0.25
Gems Orange Orange 1.6 0.09

Analysis Of

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