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What Is Paper Chromatography and How Does it Work?

Updated on June 15, 2016
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What Is Chromatography?

Chromatography is a method for separating the parts of a mixture of either a gas or liquid solution containing different chemicals. For example, pen inks are often made up of different colours. The different bonding properties of each molecule type is exploited. Chromatography is used in both qualitative and quantitative analysis of both organic and inorganic samples. This technique uses two types of substances:

  1. Mobile phase: a gas or liquid that transports the solution being tested through the other substance (water, rubbing alcohol are examples).
  2. Stationary phase: the liquid or solid through which the tested substance is carried (coffee filter paper, paper towel are examples).

It is necessary for the different chemicals in the solution fo have different properties such as molecule size or a different ability to dissolve in a solvent. The stationary phase will absorb or slow down different components of the tested solution to different degrees creating layers as the components of the solution are separated. Chromatography was invented by the Russian botanist, Mikhail Tsvet. Chemists use this process to identify unknown substances by separating them into the different molecules that make them up.

Chromatography Using Water Soluble Markers

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Six numbered strips of paper towelling with the marker colours noted. Tape the strips to a dowel. 1. Grey; 2. Dark Green; 3. Orange; 4. Dark purple; 5. Brown; 6. BlackPlace strips in a container filled with water so that the dots of marker do not touch the water and watch the colour move up the paper towel.What colours can you identify in each of the chromatograms.
Six numbered strips of paper towelling with the marker colours noted. Tape the strips to a dowel. 1. Grey; 2. Dark Green; 3. Orange; 4. Dark purple; 5. Brown; 6. Black
Six numbered strips of paper towelling with the marker colours noted. Tape the strips to a dowel. 1. Grey; 2. Dark Green; 3. Orange; 4. Dark purple; 5. Brown; 6. Black | Source
Place strips in a container filled with water so that the dots of marker do not touch the water and watch the colour move up the paper towel.
Place strips in a container filled with water so that the dots of marker do not touch the water and watch the colour move up the paper towel. | Source
What colours can you identify in each of the chromatograms.
What colours can you identify in each of the chromatograms. | Source

How Does Paper Chromatography Work?

Chromatography can be demonstrated using a simple demonstration.

What you need:

  • water soluble pens or markers of different brands or colours
  • strips of paper towel
  • water
  • rubbing alcohol
  • nail polish remover
  • straw or pencil or pen
  • cups
  • tape

What you do:

  1. Draw a line across 6 paper towel strips or coffee filter strips about 1 inch from the bottom.
  2. Tape the paper towel strip from the end opposite to the pen line onto the middle of the straw so the strip will hang when the straw is placed crosswise onto the cup.
  3. There should be enough water in the cup so that the paper towel strip touches the water but the pen line is NOT submerged.
  4. The strip should not touch the bottom of the cup.
  5. If using alcohol or nail polish remover as all or part of your solvent, place a cap of aluminum foil over the glass to keep the vapours in the glass. It will improve the results.
  6. Observe what happens.
  7. If the pen line remains unchanged in water, try with the same pen type on another strip of paper towel but substitute the alcohol or nail polish remover.
  8. Try mixing one half water and one half alcohol as your solvent and see how the colours separate.

What's Happening in Paper Chromatography?

Ink is a solution containing a number of different molecules. These different molecules have different characteristics such as size and solubility. Solubility is a molecule's ability to dissolve in a particular solvent such as alcohol, water or nail polish remover. Because of their different characteristics, each molecule travels at a different speed when pulled along the piece of paper towelling by the solvent. The lightest particles, which are not necessarily the lightest coloured particles, move more quickly and a greater distance than the heavier particles. Thus, all of the pigments that make up an ink sample are separated out.

Chromatograph of Black Ink

This chromagraph of black ink used rubbing alcohol as a solvent. Comparing a chromatogram made with the same solid medium and solvent, a comparison can be made to determine the type and brand of ink used at a crime scene.
This chromagraph of black ink used rubbing alcohol as a solvent. Comparing a chromatogram made with the same solid medium and solvent, a comparison can be made to determine the type and brand of ink used at a crime scene. | Source

Applications of Paper Chromatography

Chromatography is used in chmistry in a number of applications:

  1. Unknown substances left at a crime scene can be identified by separating the molecules that make them up. Matching this unknown chromatogram to chromatograms of known substances can help identify the unknown substance providing a clue to the crime.
  2. The ink used in a note left at a crime scene can be identified through paper chromatography. The chromatogram showing the components of the ink used in the note can be compared to chromatograms of known inks hopefully identifying the type and brand of ink used providing a clue to the crime.
  3. It is used in the sequencing of DNA and RNA.
  4. Paper chromatography is used as a qualitative analytical chemistry technique for identifying and separating colored mixtures like pigments.
  5. It is used in scientific studies to identify unknown organic and inorganic compounds from a mixture.
  6. In order to obtain a pure sample each component of the separated mixture, the separated spots on the finished and dried chromatogram can be cut out and re-dissolved.

Works Cited

Uses of Paper Chromatography. Tutor Vista.com. 2010.

Chromatography. Asistm Forensic Investigations.

Cook, Trevor. Experiments with States of Matter. New York: Power Kids Press, 2009.

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    • profile image

      William 10 days ago

      I need a help about a research of chromatography

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      mehreen prri 5 weeks ago

      what is chromatography and explain about it.

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      Tamiyah Maupin 2 months ago

      I need a answer to this question without the experiment stuff What is chromatography when it come to dying materials

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      Syedshayan 2 months ago

      Nice work mam

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      Someone Who Needs A Big Brain 3 months ago

      Agh,thanks for all the info but.. what method is Paper Chromatography used in

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      Annabeth (yes that is my real name, not from Percy Jackson) 3 months ago

      Thanks so much for posting this article Teresa Coppens, I am doing a research paper and this has helped me so much. I have cited this site for my research paper, I have checked other rescources and site, of all of them yours is the most helpful and easy to understand. I also successfully completed the experiment. Once again thank you SO MUCH!! This is a great experiment for 6th graders!

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      Scienceisawesome 4 months ago

      Thanks, this has helped me with my science research.

      This article has helped me understand chromatography more easily.

      Thanks a lot!

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      suck my 4 months ago

      thanks this really helped my science homework out a lot and it could use a bit more info, but overall this was totally helpful

    • Teresa Coppens profile image
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      Teresa Coppens 5 months ago from Ontario, Canada

      Jhen so sorry. I'm not often on this site any longer. Capillary action is the answer to question one. Question 2 was answered in the article. Different colors molecules within the dye move based on weight. Lighter molecules travel faster while heavier ones travel slower. Weight is determined by the molecular formula of the molecule.

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      Jhen 8 months ago

      I haven't gotten an answer and I need it for my lab!!!! Omg! 1)What process did the water move up the filter strip?2)what factors determine the rate at which the dye move up the filter paper?

    • Teresa Coppens profile image
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      Teresa Coppens 9 months ago from Ontario, Canada

      I am so glad it worked well for you. I love it that it inspired your siblings!

    • Teresa Coppens profile image
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      Teresa Coppens 9 months ago from Ontario, Canada

      You'll need to use the updated date which is indicated on the hub.

    • Teresa Coppens profile image
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      Teresa Coppens 9 months ago from Ontario, Canada

      Glad I could be of assistance.

    • Teresa Coppens profile image
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      Teresa Coppens 9 months ago from Ontario, Canada

      Glad it helped you out.

    • Teresa Coppens profile image
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      Teresa Coppens 9 months ago from Ontario, Canada

      Glad it helped!

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      Linley 9 months ago

      Very helpful! I am doing a science fair project about paper chromatography and this is just what I was looking for! After I read this article, I performed the experiment right away. It worked very well and my siblings were crowding around me to watch. After that, they started to do the experiment as well! This is an exciting project for all ages and it has interested me very much! Thank you!!

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      Shel 9 months ago

      When was this published I'm writing a bibliography and this is a great source so I would appreciate it if you could inform me of when it was published. Thank you

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      ... :P 9 months ago

      Thanks so much! This really help for my science homework!!!

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      nerd 9 months ago

      What is the best definition for affinity?

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      nerd 10 months ago

      thnx, this helped a lot for science fair

      wouldn't have done it without you

    • profile image

      Rakesh Kumar 14 months ago

      Its so helpful for us thnxxx.

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      reach alex uganda 21 months ago

      describe how you would perform each one of the forms of chromatofraphy

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      connor 2 years ago

      very helpful for science fair thanks!

    • Teresa Coppens profile image
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      Teresa Coppens 2 years ago from Ontario, Canada

      Thanks Tolova. I do my best to make science easy to understand.

    • Teresa Coppens profile image
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      Teresa Coppens 2 years ago from Ontario, Canada

      I hope it was helpful.

    • TolovajWordsmith profile image

      Tolovaj Publishing House 2 years ago from Ljubljana

      TLC is important analytical method for every researcher. It's not the most reliable, but it's fast and very useful at repetitive reactions, when you want just a quick check if everything in the reactor works like it supposed to. You made very clear presentation of the method. Well done:)

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      Unknown 2 years ago

      thanks, it was for my homework;)

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      shak 2 years ago

      This information was very helpful for me in doing my chemistry lab

    • Teresa Coppens profile image
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      Teresa Coppens 3 years ago from Ontario, Canada

      Sorry for the long time for a reply. Glad the article helped. Hope you did well.

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      Tresha 3 years ago

      I had to write a lad report and I used a lot of information from this article. Thank you so much

    • Teresa Coppens profile image
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      Teresa Coppens 3 years ago from Ontario, Canada

      Thanks for commenting Sarah. Hope you found the article useful.

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      sara donya 3 years ago

      it is good

    • Teresa Coppens profile image
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      Teresa Coppens 4 years ago from Ontario, Canada

      So glad you found this useful! Cheers Aslam

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      Aslam 4 years ago

      Useful

    • Teresa Coppens profile image
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      Teresa Coppens 4 years ago from Ontario, Canada

      Hey Mel. Glad to hear from you again. I have done this lab a few times in the past with high school kids. Looking forward to teaching another course where I can use it again. The technique does have a wide range of applications. Glad you enjoyed the hub. Good luck in your studies!

    • melbel profile image

      Melanie Shebel 4 years ago from New Buffalo, Michigan

      I had a chemistry lab last semester on both paper and TLC chromatography. The paper lab done was using different eluents to see which was the most effective (we used a Sharpie dot on the paper.)

      The TLC lab was a row of different analgesic drugs and then a mystery drug made up of one or more of the known drugs. We had to find out the mystery drug based on how the results compared to the known drugs. It was a pretty awesome lab... probably my favorite, actually.

      Awesome hub! Brings back a fun memory!

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