chromotogrophy lab - R ichard Yoon 4th h r Ap Chem lab I n...

Richard Yoon
4
th
hr.
Ap Chem lab
Introduction to Thin-Layer
Chromatography Kit
I.
Purpose: Using the method of chromatography, separating
compounds through absorbent and eluent reaction, identify and
study the compound (dye) by finding its polarities, chromophores,
auxochromes, and solubilizing groups.
II.
Procedures: Get 2 TLC plates and draw a horizontal line 1cm
from bottom, label 1 to 5 and M on top. Place one drop of each dye
on the watch glasses, and then using the spotters, spot each dye
vertically down from the corresponding number on the TLC plate.
M refers to an unknown mixture. Then get the chromatography
chamber ready: Pour in some eluent in two beakers with the
eluent lower than 1cm height (6mL 50/50 acetone and water), so
that the solvent doesn’t cover the dye spots. Then carefully place
each TLC strip into each beaker. Finally, cover the beakers with
parafilm and wait for a dye to reach about 1 to 2 cm from the top.
Measure the distances traveled by the dyes, record the data. (Also,
observe the TLC’s under the ultra violet in a dark room).
III. Data Collection:
Dye Keys:
Representation on
the TLC plates
Dyes D(cm) traveled
by dye
D(cm) traveled
by solvent front
1 Methylene Blue 1.2 7.7
2 Safranin 2.8 7.7
3 Eosin Y 6.5 7.7
4 Flurescein 5.3 7.3
5 Fast Green
FCF
6.9 7.3

M An unknown
dye mixture(#1)
6.9 7.3
UV LIGHT
Safranin: Pink Red
Eosin Y: Bright Pink
Flurescein: Bright Yellow
An unknown dye mixture(#1): Pink Red
IV. Data Analysis:
Find the R
f
(rate of flow) values for each dye.
Formula for R
f
:
R
f
= Distance traveled by dye
Distance traveled by solvent front
Dye R
f
colors
Methylene Blue .16 Dark baby blue
Safranin .36 Pink red
Eosin Y .84 Pink & orange
Flurescein .73 Bright yellow

Fast Green FCF .95 Greenish blue
An unknown dye
mixture(#1)
.95 On top: pink, middle:
blue, end: dark blue
1. Which dyes appear to be in your unknown?