[claip]

Hello everyone.  I have a question.  I am going to extract running coffee metabolites on HPLC and I need to use acetone, acetonitrile, sulfuric acid and formic acid.  Do all of these reagents need to be HPLC grade to do the extraction?

[rjb]

Hi Claip,

That's a decision that only you can make. It depends upon what you are trying the achieve, the reliability and certainty you require whilst also taking into consideration your financial constrains... From what I understand, HPLC grade solvents (I don't know about acids) are generally >99.9% pure and critically, contain fewer UV fluorescent impurities which could affect UV/DAD detectors and raise your baseline. Specific impurities tend also to be noted in the specs which can be helpful. Things become even more critical if you carry out LC-MS where LC-MS grade is pretty much a given.

If you're using these reagents just for extraction does it matter? I don't know your circumstances, but it seems to me that if you're running HPLC, then you certainly have HPLC grade reagents available, so why not use them?

If costs are an issue, it might be the case that your organisation has a contract with a specific supplier in place or if not it might be possible to set one up. This can make a big difference. 5L of HPLC grade ACN from Fisher costs us around 1/10th the actual list price!

Something to ponder

R