Assignment:
Chromatogram Comparisons Experiment
Read the Chromatogram Comparisons Experiment.
Perform the analysis procedure on two different brands of black felt tip pens and compare the two paper chromatograms.
Choose one of the following assignment options:
Assignment A
Take photos of your experiment showing the different color bands produced in the two paper chromatograms.
Submit photos of your experiment in an email to your instructor (provided in your course syllabus). You may take digital photos of the chromatograms or scan a copy of the chromatograms and email as an attachment to your instructor.
Assignment B
Write a 500- 750 word paper describing the experiment.
Include a description of all color bands produced in the two paper chromatograms with the order of colors that were separated out. Do the number, color and sequence of colored bands correspond between the two paper chromatograms or do they differ? What are the differences?Chromatogram Comparisons
Chromatography is a process used to separate and analyze complex mixtures and is commonly used in forensic science to isolate compounds and even separate DNA. In this experiment, you will examine and compare the ink compositions of various felt tip pens using paper chromatography, a technique similar to thin layer chromatography commonly used by forensic scientists who examine suspected altered documents.
Materials
scissors
coffee filters
ruler (preferably metric)
drinking glass
pencil
paper clip
paper punch
tap water
paper towel
2 different brands of black felt-tipped pens
Procedure:
1. Cut out a section of coffee filter 15cm x 2cm.
2. Cut a triangular point on one end of the paper strip.
3. Punch a hole into the other end of the paper strip with a hole-punch.
4. Place a small spot of ink near the point of the paper and allow the spot to dry.
5. Repeat this process four more times.
6. Add about 2-3 cm of water into a drinking cup.
7. Open up a paper clip and place it through the paper hole so that you can hang the paper strip from a pencil resting on the top of the glass.
8. Position the paper strip so that the strip hangs from the center of the glass and does not touch the sides of the cup.
9. The pointed end of the paper strip should be immersed in the water. The ink spot must be above the water line.
10. Allow the water to rise to the top of the paper strip.
11. Remove the paper strip from the water cup and place it on a paper towel to dry.
12. Mark the paper towel with the brand/color of ink that was examined.
13. Repeat this procedure with the second black felt-tipped pen.
Tips:
If you live in a dry climate then you may have to perform the experiment in a sealed plastic bag to avoid evaporation of the water.
Permanent markers such as Sharpie will not work in this experiment.
The experiment will work best with black inks.
Here is a list of some water soluble ink felt tip pens that should work in the experiment:
- Rose Art
- Crayola
- Papermate-Flair
- BIC, Expresso
- Expo Vis-à-vis
- Skill craft
- Unisom
- Triplus fine liner
- Onyx
- Finesse
- Penteck and Sanford Mr. Sketch Water Color Marker