[Daimai]

Hello. I am going to do some research on tea.

Basically, what I want to do is analyze the compounds in the tea depending on what temperature the water has, how long I have the teabag in the water etc.

What I was thinking of doing are two things:

1. Column-chromotography on the tea, and then I analyze the different compounds I get with spectrometry.
The problem with this method would be that I'm doubting I'll get any useful information from the spectrometer since the concentrations of the compounds might be too small. Also I would need reference solutions, and there are A LOT of compounds in tea, I don't even know where to start.

2. Thin layer chromatography, basically same problem. I need to try different eluents, different reference solutions etc. Even if I know that tea contains caffeine, how can I find pure caffeine to use as a reference? Not even mentioning the other compounds in the tea.

3. Mass-spectroscopy; my school probably doesnt even have that.

Basically, I am looking for any knowledgeble people who can give me some tips and help me out.

I'm doing this is a project that is supposed to span 6 months, so I do have a fair share of time, but it's still pretty daunting.

Also I'm a senior in high school so we don't exactly have the most sophisticated equipment in our school.

Thanks!

[Arkcon]

I'm going to suggest, that for a high school project, you'll need to think smaller.  Suggestion:  you have a broad outline, the effect of brewing temperature on the extraction of components from tea.  You have two analysis methods, column chromatography and TLC.  Now, run it past your teacher, and see what they suggest.  There are probably hundreds of water extractable components in tea, some that are very similar to each other in properties.  Even with the best of equipment and intimate knowledge of the components, you'll have to simplify what you're looking for.

[Daimai]

Hello Arkcon! Thank you for taking the time to read my thread and respond.

I listened to your advice and decided to find what gives tea it's taste.

I found the following table:

Compounds  | Flavor
-----------------------------------------
Polyphenol   | Astringent
Amino Acids | Brothy
Caffeine      | Bitter
Theaflavins  | Astringent
Thearubigin  | Ashy and slightly astringent
----------------------------------------------
These are the compounds I'm primarily looking for, then.



Is there any site or book I can find a table of R_f values for different eluents? It would be very much appreciated. My teacher told me to search for a good eluent but I don't even know where to begin.

[Arkcon]

You're unlikely to find a canonical list of Rf values, they vary too much from system to system.  If you go TLC, you'll probably have to determine them for your chosen solvent and plate system experimentally using a standard.  You can buy pure caffeine for use as a standard, many professional labs keep it around to test a number of things -- HPLC's or a spectrometer, as examples.  You may be able to buy a small amount of some of the others.  Once you've figured out how to get a good Rf from 3 or 4 of the compound classes you've selected, you can run a good strong brewed cup of tea and compare.  Then you can do the experiment you described.