Ink Analysis Lab
There are three known pens available. These samples
will be compared with the unknowns.
1. Measure 0.5 cm from the top and bottom of the chromatography
paper. Lightly draw a line across the paper at these points IN PENCIL.
2. Determine where you will place your seven samples by marking, under
your pencil line, where the ink samples will go.
3. For the three known samples, the principal's pen, and the two suspects
pens, place a small amount of ink above your labeled paper. Firmly press
down on the paper with the pen. You want to make a small dot.
4. For the crime scene sample, you will need to extract the ink from
the check. To do this, cut a small square from the check that includes
the pen mark. Add the alcohol/water solution to this sample. This will
dissolve the ink. Using a micropipette, place a drop of this extracted
liquid to the chromatography paper where you marked "Crime Scene."
5. Staple the ends of the chromatography paper together with the ink
marks on the outside. DO NOT overlap the paper! Place this inside the
plastic cup. DO NOT let the chromatography paper touch the side of the
6. Add 2:1 propanol/water to the Petri dish. Place the chromatography
paper and plastic cup in the solution.
7. It will take 20-25 minutes for the mobile phase to end. You want
to remove your chromatography paper from the Petri dish when the liquid
is at the upper pencil line.
8. Remove chromatography paper from solution. Using a pencil, circle
the points where the ink has traveled and separated. Dispose of solution
as instructed. Hang your chromatography paper up to dry.
1. What does "polar" mean? Give an example
of a polar substance. (2 pts.)
2. What does "non-polar" mean? Give an example of a non-polar
substance. (2 pts.)
3. What does the phrase "like dissolves like" mean? (2 pts.)
4. Why is thin layer chromatography an important lab tool? (2 pts.)
5. List two components of ink. (2 pts.)