DIY Chromatography

What could be simpler?

Safe­ty pre­cau­tions

Warn­ing! Only un­der adult su­per­vi­sion


  • pa­per cof­fee fil­ter;
  • brown felt-tip pen;
  • cit­ric acid;
  • wa­ter;
  • cot­ton wool;
  • plate;
  • glass.

Step-by-step in­struc­tions

Place a pa­per cof­fee fil­ter on a suit­ably-sized plate. Use a brown felt-tip pen to draw and fill in a cir­cle in the mid­dle of the fil­ter. Dis­solve a tea­spoon of cit­ric acid in a glass of wa­ter and dip a piece of cot­ton wool in the re­sult­ing so­lu­tion. Put the wet cot­ton wool on the cir­cle. Watch as the brown spot turns into mul­ti­col­ored rings!

Process de­scrip­tion

It would seem that the brown mark­er is filled with brown dye, but it isn’t! And chro­matog­ra­phy can help you prove this! Chro­matog­ra­phy is a method of sep­a­rat­ing and an­a­lyz­ing sub­stances based on the dif­fer­ent mo­bil­i­ty of sub­stances be­tween two phas­es – a sta­tion­ary phase (in this case, the cof­fee fil­ter) and a mo­bile phase (the cit­ric acid so­lu­tion). Due to the cap­il­lary ef­fect, the cit­ric acid so­lu­tion even­ly wets the pa­per and car­ries the brown dye with it, which di­vides into sev­er­al col­ors as it moves far­ther from the cen­ter! The dyes com­pris­ing the brown dye in the pen dif­fer from each oth­er in their chem­i­cal na­ture, and move through the pa­per at dif­fer­ent speeds.

Cool ex­per­i­ments await you in the MEL Chem­istry sub­scrip­tion!