How does it work with purity testing?

If you have a reference standard, and known methods, you can use HPLC to test both purity and identity. The retention times will differ if a compound is not the right one, even if the purity is good. But if you do not know the identity of the compound, the HPLC might tell you it is 99.7% pure. However, it could be a different compound.

So let's say you want to test Piracetam. If you have a reference standard from somewhere like Sigma Aldrich, then you can run that through the HPLC, then run your sample through the HPLC. The retention times should match, and the % area of the peak will be your purity. Then the test should only be $200-400. It might be more if the lab has to purchase a new standard from Sigma, but not much.

Now let's say you want to test a new compound like Nitromemantine. Well Sigma Aldrich does not have a reference standard for that. So you will not know the retention times you are looking for. This means you have to find the identity of the compound first, to confirm you have the correct molecule. Then you can HPLC it to get purity.

If the compound has an FTIR spectral database entry, you can FTIR it and have the algorithm compare it to the database. If that is the case, then usually the lab will charge the same amount as a regular HPLC. If the compound has no spectral database entry, then you will need to run a more expensive NMR or mass spec test. Which one is better depends on the compound itself.

Mass spec will either us a gas chromatograph (GC) or a liquid chromatograph (LC) to separate the sample, and then test the mass of each component. In Nitromemantine's case, you would use an LC/MS, and the mass you would be looking for is 268.35g/mol. That would tell you that the mass is correct for the compound you are looking for. That would add an extra $400 or so to the bill.

If you wanted to see if the structure itself is correct, an NMR would tell you the number of protons in the sample, and where they are located. That would give you total confirmation that the molecule you had is correct, then allow your HPLC purity results to be validated for the correct substance. An NMR would run $300-400 more.

The time it takes, and the amount of sample to send, will depend on how deep they have to get into it. Usually a lab will ask for 3-5 grams of a compound, so they have more if they need to run extra testing. A regular HPLC should only take a couple weeks at most from a lab. The testing itself only takes a couple hours. However, the lab always has other people in front of you. So it takes them time to get to your test.