CSI: ChromatographyCSI: Chromatographyof individual inks or identifying

multiple inks

CSI Experiment: Ken, Barbie, and Skipper (Barbie’s little

sister.)

KEN IS MISSING!!!!!KEN IS MISSING!!!!!• Good thing he left a note.

– “Dear Friends, I can not find the will to go on like this anymore. I am so sorry. Ken”

• Did he run off without telling anyone… or did a CRIME occur???

• What are a few ways that you might be able to CSI test this note to find out if Ken wrote it?

• Handwriting Analysis—YES! But I have NO samples of Ken’s handwriting for you.

• Chromatography!!! Which is what we will be learning about today!– I have collected pens from the two suspects

the police have detained. Here are our two suspects.

Suspect #1: Barbie

– alibi: shopping, but she didn’t buy anything…has no receipts to prove it and went alone (no one can verify this)

– Police are suspicious …. have you seen all that girls’ clothes? She didn’t buy anything? Whatever!

– A mutual friend reports that Ken and Barbie had a fight recently.

Suspect #2: Skipper

alibi: having a tea party with her invisible friends. She says her invisible friends can verify her whereabouts, but police can’t find them anywhere.Police are suspicious …. Why can’t these friends be found for an interview? A school friend reports that Skipper was upset about a fight Ken and Barbie had about her. Barbie wanted to take Skipper along with them on a trip, but Ken did not.

YOUR MATERIALS

• Gather your materials for each group– Piece of note written with Ken’s name signed.– 3 pieces of filter paper with a punched out

hole at the top and point at the bottom.– Paperclips. – Long pencil or wire.– Teacher will instruct you how to use the

paperclips and pencil and how to conduct a minor ink chromatography experiment.

INK CHROMATOGRAPHY

• Take your pointed filter paper and 3 pens. Make a dot of ink like the one in the example to the right.

Ink Dot from pen A

Label paper “Pen A”

Pen A

You should now have samples from all 3 pens like below.

Pen A Pen B Pen C

Chromatography• CSI scientists use

Chromatography as a method that scientists use to separate components of a colored mixture such as ink, pigments, and dyes. Investigators and forensic scientists often use chromatography when trying to solve a crime.

Notice that the brands on the pens are all different.

• What do you think black ink will look like all spread out?

• Is black made from black ink only, or made of many colors?

• Will you be able to tell the difference between pens? How?

Attach the paper clips through the points at the bottom.

Pen A Pen B Pen C

Time to run the pencil through the holes.

Pen A Pen B Pen C

Alright! Last step! Hang the paperclips and very bottom of the paper into the water. Make sure the water does not touch

the ink directly!

Pen A Pen B Pen C

• Students marked black ink onto filter paper, exposed the filter paper to water and watched as the water and ink traveled through the paper, revealing the different colors that make up the color black. Different types of black ink created different “rainbow” patterns of color according to their chemical makeup.

Create an Experiment to determine who wrote the note…

• If Ken did, the suspects will be released.

• If Barbie or Skipper wrote the note, police will need to bring them in for further questioning…

• So, what do you need to do to find out who wrote it?

• What do you compare it to? (the control!)

What did you find!?

Upon further investigation…

• Barbie had locked Ken into the closet by telling him to go get the suitcase and help her pack for the trip.

• She was upset about their confrontation.

• WARNING: When we are upset with someone we should use our words and not give into acts of weirdness or violence

LAB #2…Can CSI specialists tell if a document is altered by someone?

• Yes! They can check and see if it is written with two inks.

• A document that someone might want to alter.

• A grade on a report card or paper

Lab#2: The suspicious B-

• It is Monday. Billy brought home his backpack from school.

• Billy’s mom went through it to see what homework he had to work on that night.

• Billy’s mom found his research paper rough draft with a note from the teacher “Needs more work”. It also has a score of a B-.

• The research paper is due Friday. When mom asks Billy about the paper he states he just has a few changes to make before Friday to raise his grade to an A… What do you think/ notice? Anything suspicious to you?

How can Billy’s mom determine if that grade is accurate or has been

altered?

• Think Chromatography….

• If it was written with one pen, what would it look like…

• If it was altered by a second pen, what would it look like…

• TIME FOR YOU TO FIND OUT!?

• What is your conclusion?

YES! Billy totally changed the D- to a B-. See the before and after? Testing of the B- should show different inks

than the message above “Needs more work”

JUST FOR FUN!• Chromatography of colors.• Predict what colors make up

the following:– YELLOW– RED– BLUE– PINK– LIGHT BLUE– GREEN– LIGHT GREEN– ORANGE– BROWN

USE YOUR KNOWLEDGE OF CHROMATOGRAPHY TO TEST THESE COLORS ON SEPARATE STRIPS AFTER YOUR PREDICTIONS. YOU WILL HAVE TO MAKE YOUR OWN STRIPS THIS TIME!