Clinical perspective, offered as context rather than as advice.
HPLC results interpretation for certificates of analysis: when you get your Janoshik report back, here's what the numbers mean:
- Purity %: Should be >97%. Below 95% is concerning.
- Retention time: Should match reference standard for the peptide
- Related substances: Degradation products should be <2% total
- Single impurity: No individual impurity should exceed 1%
My last batch: 99.3% purity, 0.1% total related substances. Clean chromatogram with single sharp peak at expected retention time. Exactly what you want to see.
stefan_berlin said:Mass spectrometry confirmation for certificates of analysis: beyond HPLC purity, mass spec tells you the molecule's exact molecular weight.
Thank you for spelling out the reasoning rather than just the conclusion. Sending this to two other people who asked me the same thing last week.
From the other side of the consultation, briefly.
I tested my certificates of analysis batch through Janoshik — 97.6% purity. That's within acceptable range for compounded peptides. Turnaround was 10 business days.
The test costs ~$126 but gives you actual HPLC chromatography data plus mass spec confirmation. For the peace of mind alone, it's worth every penny. I test every new batch from a new vendor.
Sigma-Aldrich — Research-Grade Standards
Certified reference materials, analytical reagents, and research-grade standards for peptide verification. Trusted by laboratories worldwide.
Shop Reference StandardsDr.LeslieOBGYN said:I tested my certificates of analysis batch through Janoshik — 97.6% purity.
This matches mine closely enough to be worth saying so out loud.
Moderator note: reminder that nothing in this thread is medical advice, and that clinical claims need a source. Report rather than reply if it drifts again.