MOHAWK COLLEGE OF APPLIED ARTS AND TECHNOLOGY
CHEMICAL AND ENVIRONMENTAL TECHNOLOGY DEPARTMENT
Lab Report
ROOM NO: FE E309
EXPERIMENT NO : 8
TITLE
: Thin Layer Chromatography of Food Dyes
Submitted by
: Lyndsay Grover
Class
: BIOL 10000 lab.
Partners
: Awatif Hagelamin
Instructor
: Farag Soliman
Date lab performed : February 3, 2011
Date of submission
: February 10, 2011
FENNELL CAMPUS
HAMILTON, ONTARIO
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Purpose:
The purpose of this experiment was to observe the reactions of food dyes with thin layer
chromatography paper in order to find the components of an unknown solution. The practical
applications of thin layer chromatography involving food dyes are to find the known food dyes in an
unknown solution, which could be useful in safety testing as well as testing for food dyes in terms of
allergies.
Procedure:
We began by preparing four small sheets of thin layer chromatography paper, two per person so there
would be duplicates of the results. We then pipetted five known dyes and two unknown solutions onto
the paper. We then allowed them to develop in the solvent. After the solvent had raised a desirable
amount up the chromatography paper we removed it, allowed it to dry and then measured the solvent
front, distance to dots and the computed the Rf values.
Data/Observations:
Table 1
Colour in Solution
Colour as a Dried Spot Colour After
Development
Dark Red
Red
Dark Red
Dark Purple/Red
Burgundy
Fuchsia
Orange-Yellow
Orange
Orange, Yellow
Dark Green
Green
Blue, Yellow
Dark Blue
Blue
Blue, Pink
Dark Red/Orange
Yellow
Yellow, Pink
Dark Red/Brown
Brown
Red, Blue, Yellow
Dyestuff
Pink
Cochinea
Egg Yellow
Green
Blue
Mixture A
Mixture B
Dyestuff
Spots Observed
Pink
a
b
c
a
b
c
a
b
a
b
a
b
c
a
b
Cochinea
Egg Yellow
Green
Blue
Mixture A
Table 2
Distance to
Solvent Front
(cm)
3.6
3.6
3.6
3.6
3.6
3.6
3.6
3.6
3.6
3.6
3.6
3.6
3.6
3.6
3.6
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Distance to Spot
Center
(cm)
0.3
0.9
2.1
0.3
0.9
2.1
0.4
0.9
0.3
0.5
0.4
1
1.3
0.6
1.3
Rf values
0.0833
0.25
0.583
0.0833
0.25
0.583
0.111
0.25
0.0833
0.138
0.111
0.277
0.361
0.166
0.361
Mixture B
c
d
a
b
c
d
3.6
3.6
3.6
3.6
3.6
3.6
1.7
2.3
0.3
0.6
0.9
1.1
0.472
0.638
0.0833
0.166
0.25
0.305
Calculations:
0.3/3.6cm= 0.0833
0.9/3.6cm= 0.25
2.1/3.6cm= 0.583
0.4/3.6cm= 0.111
0.5/3.6cm= 0.138
1.0/3.6cm= 0.277
1.3/3.6cm= 0.361
0.6/3.6cm= 0.166
1.7/3.6cm= 0.472
2.3/3.6cm= 0.538
1.1/3.6cm= 0.305
Discussion:
In this experiment there are very few sources of error due to the experiments simplistic nature but
these errors could dramatically change the results if they were to occur. Possible sources of error could
include: dye contamination, incorrect solution strength, and insufficient development time.
Dye contamination could have occurred if one dye bled over into the other dyes lane, thus corrupting
the reaction for that dye because of a foreign component. Incorrect solution strength could have not
included enough of the component needed to create the proper reaction with the food dyes, preventing
the separation of components in the dye. Insufficient development time would mean that the reaction
was not able to be completed fully so the dye components may not have risen up the solvent front to
their proper height or may not have been able to completely separate.
I do not believe any of these sources of error occurred in our experiment. There was no dye
contamination since none of the dyes bled over into the other lanes. The solution seemed to be the
correct concentration since the dyes did react with the solvent and did move up with the solvent and
separated in the process. As well the chromatography paper was left in the solvent for a sufficient
amount of time and was able to rise up to the desired height.
Conclusion:
When observing the spots created by the known dyes we can apply these known patterns to the
unknown mixtures to determine their components.
For Mixture A it appears to have two components to the mixture, as to the dyes involved it is still
unknown since it does not match any of the known dyes. The only known dye I could guess as to be one
of the components would be egg yellow.
For Mixture B it appears to have 3 components to the mixture. The components it contains appears to
be pink, green and blue. The first dot seems to be the base dot for red slightly tinted by the base dot for
green. Then follow by the yellow component of the green dye, then the blue and the red with the small
yellow component at the very top.
So in summary Mixture A contains two components though still unknowns and mixture B contains
three components composed of pink, green and blue.
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