Dr.ReproEndo said:Mass spectrometry confirmation for certificates of analysis: beyond HPLC purity, mass spec tells you the molecule's exact molecular weight.
Vendor quality matters when discussing certificates of analysis. I've tested my last 6 batches through Janoshik and purity has ranged from 98.9% to 100.7%. Consistency is key.
For anyone new: always request the COA, and consider independent verification. The $300 for a Janoshik test is worth the peace of mind.