chromolab

Topics: Thin layer chromatography, Chromatography, E number Pages: 11 (2003 words) Published: May 24, 2014
Chemistry 100Experiment #2: Chromatography of Food Dyes Name: Cassandra DeVauxDate: April 17, 2014

Purpose:
To learn how mixtures of compounds can be separated and what food dyes are found in certain foods

Introduction:
In this exercise we will separate food dyes from a variety of sources. We will first gather data on known dyes where we know how many substances make up the dye. Then we will collect data on some samples where we do not know the make-up. We will compare our known dyes with our unknown samples and be able to make a determination of which dyes are in our unknown samples. Chromatography is a technique used to separate substances dissolved in a mixture. Chromato means color and graphy means “to write.” Paper is the medium used to separate the components of the mixture. Our known substances will be FD&C dyes that are used in food products. Currently, there are seven approved food dyes. These are: Red 3

Red 40
Blue 1
Blue 2
Yellow 5
Yellow 6
Green 3 (**will not be used in this lab)
To determine the components of our unknown, we will calculate the retention factor (Rf) of each spot. The Rf is a unitless mathematical expression for the distance traveled by the dye molecules divided by the distance traveled by the solvent front. The Rf factor will be constant for a given dye provided all conditions in the experiment are kept constant.
distance travelled by dye
Rf = ---------------------------------------
distance travelled by solvent

Data for Sheet 1:
1. Using the drawing function on your word processer, draw a picture of your chromatography sheet once the dots are applied, but before you have set it into the solvent. (you can also take a picture and insert it here)

2. Using the drawing function on your word processor, draw a picture of your chromatography sheet once the experiment is over. Mark the solvent line and circle each separate spot for each of the samples. For example, if Red 40 separated into three different colors, and thus three spots, then I would have three circles above the original Red 40 spot.

3. Now record your data in table form(**some boxes may be left blank if data does not exist) Experiment Samples
Distance Traveled by Spot (mm)
Distance traveled by solvent (mm)
Blue 1
61mm
60mm
Blue 2
0mm
60mm
Yellow 5
43mm
60mm
Yellow 6
35mm
60mm
Red 3
8mm
60mm
Red 40
24mm
60mm
Unknown 110
Red Spot 28mm
Blue Spot 36mm
60mm

Kool-Aid Grape
Distance Traveled by Spot (mm)
Distance traveled by solvent (mm)
Spot 1 (Red)
24mm
70mm
Spot 2 (Blue)
52mm
70mm
Spot 3
N/a
N/a

Kool-Aid Strawberry
Distance Traveled by Spot (mm)
Distance travelled by solvent (mm)
Spot 1
23mm
60mm
Spot 2
N/a
N/a
Spot 3
N/a
N/a

Data for Sheet 2:
1. Using the drawing function on your word processer, draw a picture of your chromatography sheet once the dots are applied, but before you have set it into the solvent.

2. Using the drawing function on your word processor, draw a picture of your chromatography sheet once the experiment is over. Mark the solvent line and circle each separate spot for each of the samples. For example, if Red separated into three different colors, and thus three spots, then I would have three circles above the original Red spot.

3. Now record your data in table form (**some boxes may be left blank if data does not exist) Experiment Samples
Distance Traveled by Spot (mm)
Distance traveled by solvent (mm)
Red
Spot 1
34mm
61mm

Spot 2

Spot 3

Yellow
Spot 1
41mm
61mm

Spot 2

Spot 3

Green
Spot 1
44mm
61mm

Spot 2
64mm

Spot 3

Blue
Spot 1
37mm
61mm

Spot 2
44mm

Spot 3
64mm

MM Green
Distance Traveled by Spot (mm)
Distance traveled by solvent (mm)
Spot 1
31mm
61mm...
Continue Reading

Please join StudyMode to read the full document

Become a StudyMode Member

Sign Up - It's Free