Column Chromatography

1
Column Chromatography
Chemistry 101 Laboratory

• Separating a mixture of food coloring.

2
A disposable pipette tip will save you from
having to manipulate hot glass tubing.

• With a small glass rod, push a LOOSE pellet of
  cotton into the pipette tip. DONT PACK IT
  TIGHTLY!!

3
You will be provided with a two-foot length of
glass tubing.

• You must cut the tubing into TWO 1-foot lengths.
• This will give two columns (which you can share)!

4
This is easier than you think . . .
5

• Dont put the hot glass down on a cold bench top.
• Dont pick it up again until you are SURE it has
  cooled.

6
Fit the glass column onto the pipette tip.

• If the fit is not secure, a bit of scotch tape
  will help secure the tip to the column.

7
Select a suitable cork to support the column.
8
If the hole is too small, use the rat-tail file
if it is too big, cut a slot out of it.
9
With a piece of tubing, fit a small funnel to the
top of the column.

• This will make it easier to pack the column.

10
Fit the column through the cork stopper and
clamp it to a ring stand.

• Obtain several grams of chromato-graphic alumina
  and prepare to pack the column.

11
FIRST, add a bit of clean sand on top of the
cotton.

• No need to overdo it!

12
Now, add the alumina to within 10 cm (3-4 inches)
from the top!

• This may be more difficult than you expect and
  will test your patience. If you rush it,
• it will cause you even more difficulties.

13
Now, add a bit more sand to the top of the
alumina.

• Remove the funnel, and prepare the 70 percent
  methanol eluent.

14
Liquids do not mix well in small diameter
vessels (remember pousse café?)

• So, -- pour the mixture into a beaker and
• MIX IT THOROUGHLY.

15
When all is ready, add 3 4 drops of the dye
mixture to the top of the column.

• Some of the mixture may cling to the glass walls
  of the column.

16
FIRST,let the dye mixture go just below the
layer of sand.

• THEN, rinse the walls of the column with a few
  drops of the 70 methanol eluent.

17
As the column drains, continue to add eluent to
the top of the column.

• When the leading color is half way down, fill the
  column. Label it with your name, and leave it to
  drain until the next lab.