Paper Chromatography

[colors]

I'm doing paper chromatography for my science fair and I'm wondering if anybody can help me.

So far, I made samples with standards and powdered- drink mixes with ethyl alcohol. However I'm not sure what my solvent is going ot be made up of. I know it is going to be made up of ethyl, water, and salt but not the amounts. If anybody can help me out, it would be very appreciated. Thanks.

[tom jupille]

Chemistry is an experimental science. One of the nice things about paper chromatography is that you can do several experiments "in parallel" (in other words, more or less at the same time).

So set up a series of five jars and five strips of paper. Place in the jars different mixtures of ethyl alcohol and water, something like this:
Jar 1: 100% water
Jar 2: 75% water, 25% alcohol
Jar 3: 50% water, 50% alcohol
Jar 4: 25% water, 75% alcohol
Jar 5: 100 alcohol

Spot a couple of your samples on the paper and run in each solvent. Some of them will probably be "too strong" (all the colored compounds will wash up right along with the solvent). Some of them will be "too weak" (the colored compounds will not move at all). Hopefully, one of them will be "about right". If necessary you can "fine tune" the composition, changing the alcohol percentage by 5% up or down.

Once you have that nailed down, put the same water/alcohol mixture in each jar, but change the salt concentration (0% 0.2%, 0.5%, 1%, 2%). Again, you can "fine tune" to find the amount of salt that gives the best results.

Finally, remember that there is no "universal" best solvent; each drink mix may require a different composition. You won't know until you do the experiments!