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.

Questions & Answers

  • What is a paper chromatography's mixture?

    Usually rubbing alcohol is used as a solvent to separate colors of ink.

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    • Teresa Coppens profile imageAUTHOR

      Teresa Coppens 

      4 weeks ago from Ontario, Canada

      Happy to hear that Sofia!

    • profile image

      Sofia 

      4 weeks ago

      I understand it very well

    • profile image

      angel 

      3 months ago

      I understand about Chrmatography

    • profile image

      Sherece 

      3 months ago

      I understand thank u

    • profile image

      Rebekah 

      5 months ago

      Thank you very much for helping!!

    • profile image

      rejo 

      7 months ago

      Anx a lot but what is another type of chromatography and how to define the changes of liquids on the chromatography

    • profile image

      rex 

      7 months ago

      thank you

    • profile image

      online tutoring 

      8 months ago

      Thnx

    • profile image

      Luna 

      8 months ago

      Useful, thx!

    • profile image

      Bigey 

      11 months ago

      Very useful, thank you!

    • profile image

      Sathwika 

      12 months ago

      Super

    • profile image

      mridul bansal 

      12 months ago

      this is a very useful information for a child to understand that what is chromatography. but if there would be more pictures related to the steps then it would me more understandable and easy. if there would be a video also then i am sure that this page is liked by all. some better steps are also required. this information is very simple to understand by a 9th class standard student but if a 8th class or below student want to understand that what is chromatography then he could not understand from only this much information . i prefer you to add more videos images at every step and more information to this project.

    • profile image

      Ana 

      12 months ago

      Needs to be a clearer explanation of how it works.

    • profile image

      Aina 

      13 months ago

      Very useful thank you soon much

    • profile image

      William 

      14 months ago

      I need a help about a research of chromatography

    • profile image

      mehreen prri 

      15 months ago

      what is chromatography and explain about it.

    • profile image

      Tamiyah Maupin 

      16 months ago

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

    • profile image

      Syedshayan 

      16 months ago

      Nice work mam

    • profile image

      Someone Who Needs A Big Brain 

      17 months ago

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

    • profile image

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

      17 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!

    • profile image

      Scienceisawesome 

      18 months ago

      Thanks, this has helped me with my science research.

      This article has helped me understand chromatography more easily.

      Thanks a lot!

    • profile image

      suck my 

      18 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 imageAUTHOR

      Teresa Coppens 

      19 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.

    • profile image

      Jhen 

      23 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 imageAUTHOR

      Teresa Coppens 

      23 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 imageAUTHOR

      Teresa Coppens 

      23 months ago from Ontario, Canada

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

    • Teresa Coppens profile imageAUTHOR

      Teresa Coppens 

      23 months ago from Ontario, Canada

      Glad I could be of assistance.

    • Teresa Coppens profile imageAUTHOR

      Teresa Coppens 

      23 months ago from Ontario, Canada

      Glad it helped you out.

    • Teresa Coppens profile imageAUTHOR

      Teresa Coppens 

      23 months ago from Ontario, Canada

      Glad it helped!

    • profile image

      Linley 

      23 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!!

    • profile image

      Shel 

      24 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

    • profile image

      ... :P 

      24 months ago

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

    • profile image

      nerd 

      24 months ago

      What is the best definition for affinity?

    • profile image

      nerd 

      24 months ago

      thnx, this helped a lot for science fair

      wouldn't have done it without you

    • profile image

      Rakesh Kumar 

      2 years ago

      Its so helpful for us thnxxx.

    • profile image

      reach alex uganda 

      2 years ago

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

    • profile image

      connor 

      3 years ago

      very helpful for science fair thanks!

    • Teresa Coppens profile imageAUTHOR

      Teresa Coppens 

      3 years ago from Ontario, Canada

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

    • Teresa Coppens profile imageAUTHOR

      Teresa Coppens 

      3 years ago from Ontario, Canada

      I hope it was helpful.

    • TolovajWordsmith profile image

      Tolovaj Publishing House 

      3 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:)

    • profile image

      Unknown 

      3 years ago

      thanks, it was for my homework;)

    • profile image

      shak 

      3 years ago

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

    • Teresa Coppens profile imageAUTHOR

      Teresa Coppens 

      4 years ago from Ontario, Canada

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

    • profile image

      Tresha 

      4 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 imageAUTHOR

      Teresa Coppens 

      4 years ago from Ontario, Canada

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

    • profile image

      sara donya 

      4 years ago

      it is good

    • Teresa Coppens profile imageAUTHOR

      Teresa Coppens 

      5 years ago from Ontario, Canada

      So glad you found this useful! Cheers Aslam

    • profile image

      Aslam 

      5 years ago

      Useful

    • Teresa Coppens profile imageAUTHOR

      Teresa Coppens 

      5 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 Palen 

      5 years ago from Midwest USA

      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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