Comment · Mon, October 31, 2022
What is the difference in these two substances? Is one more pure than the other?
What they were answering
Direct reply to the original post in this thread.
u/MisterYouAreSoDumb
You can't tell shit from those chromatograms, because peak purity at a single wavelengths means nothing to assay/purity. The baseline drift is one thing. Sometimes your methods have those, and it doesn't necessarily mean the integration of the peak is not valid. It can happen in complex matrices. However, for a pure synthetic product like phenibut HCL there is no reason to not optimize the methods to resolve that. It's lazy chromatography. The bigger issue is that you are just seeing peak purity from a manually integrated peak at a wavelength that tends to hide impurities. We also don't know the dilution factors and sample prep. Proper chemistry would be to use a PDA detector and compare peak areas between the QC sample and a validated reference standard at an appropriate wavelength, and then do spike recovery and validation work to ensure your methods are actually telling you what you think they are. This looks like someone sent a sample of phenibut to a lab that doesn't normally assay it, and they just ran basic testing to get a quick peak purity analysis.
The report is from Chromeleon, which is a Thermo software product. Thermo also makes the Vanquish HPLC/UHPLC systems, so this result could have been on a Thermo Vanquish HPLC. We use Chromeleon on our Thermo GC, but we use Waters' UPLCs for most of our liquid chromatography, so we use Empower for all our LC chromatograms. The reports you posted could be from any lab using Chromeleon for their LC systems. It is interesting that the first report says: "Gastrodin and Phenibut Purity HILIC." That could mean this lab tweaked a gastrodin method to get a quick analysis of phenibut. However, the validity of that is questionable. HILIC stands for "hydrophilic interaction liquid chromatography," which is normal phase chemistry, not reverse phase. Definitely not common for phenibut assay. I certainly wouldn't be confident in the purity/assay of the batch based on these reports.