[Nyaiffy]

Hi!
For some of my coursework I have to design and carry out an analytical experiment on some unknown drug samples, one of mine is 'Clear liquid in tube' - that's all I have to go off.
I'm thinking Presumptive testing (Would Marquis test work?), TLC & HPLC but straight up I'm so awful at chemical analysis, it's always been my worse module and I have no idea where to start.
I have to talk about things such as level of sampling and why it's statistically valid, sample prep and how to determine if my data correct & accurate, this may as well all be in a foreign language to me, if anyone can offer any advice with any of this I'd be eternally grateful!

[MOTOBALL]

Pas de Panique !!!
Start with some basic thoughts.

1. Does "clear liquid in tube" mean colourless or no solid material visible?

2. If colourless, what is needed to give colour and is therefore absent from your sample?

3. Is the clear liquid an aqueous solution, or a solution in an organic solvent?

4. How would you test this? Think about miscibilities of liquids.

5. If you were to spot onto a TLC plate, but NOT run the plate with a solvent system, how would you detect organic compounds ?

I will come back to this later....

Regards,
Motoball

[jeffmoonchop]

It sounds an experiment we had to do in school, like the classic separation of organic liquids. I would recommend running GC. If you have GC-MS the products would probably be in the library so you can tell what they are easily.

However, if it is actually a drug dissolved in water, HPLC should be ok. If its just one compound in the solvent you'll just get the one peak. But separation itself won't tell you what it is. You may need to run NMR, MS etc.

Once you decide what it may be from those analyses, you can run HPLC with the known pure material in a vial, alongside a vial of the sample. If the retention time is the same as the peak, you can be pretty confident its the right thing.

[marquis]

You might be able to do a uv/vis scan and if it that way.  Non destructive and all that.