Chromatography Lab

           Paper chromatography is a technique which permits one to separate the components present in a mixture.  Two basic concepts underlie this process; capillary action and solubility differences of the components.

           Leaving a corner of a paper towel in a dish of water demonstrates capillary action as the water molecules are attracted to the paper and move up the towel.  If the end of a strip of paper were to come into contact with a solvent, the solvent would move up the paper due to capillary attraction to the paper.  In general, the more soluble the component is in the solvent, the higher it will travel up the strip of paper; in addition, the component will travel even higher the less attractive it is to the chromatography paper.

 Possible solvents:  water, alcohol, peroxide, Sprite, vinegar, ammonia, bleach…

Possible papers:  paper towel, filter paper, coffee filters, newspapers…

Possible inks:  any marking pens, liquid ink pens (brown is usually a combination of colors)

 Extra idea:  What would happen if you applied the extraction from tree leaves to the chromatography paper?  What changes, if any, would you have to make to investigate the extraction?  (hint: in order to separate these pigments, they must be soluble in the liquid being used as the solvent.)

 

During lab: 

1)     set up code sequence for: solvent, paper, ink type/color

2)     write code on notebook paper as well as chromatogram (as your are preparing it)

3)     as chromatogram develops (drys) decide if there was a color separation.  Note this on notebook paper.  If no color separation note this as well.  Keep chromatograms that did show a color separation in one stack and the ones that did not in another stack.  Staple these to the notebook paper (and label them) when finished.  Ones that don't work count as well as those that do show separations.

4)     20 - 24 strips = C     25 - 30 = B      30 +  =  A

 

Things you need to bring to lab if available:  plastic cups, different types of absorbent paper, pencils or straws to lay across the cup and suspend the chromatograms, and the most important: a variety of color markers, pens, inks.   I will provide the solvents and some papers and pens.   On your notebook paper that you will attach the chromatograms please indicate the number of type of items you brought (for bonus credit).