Dr.PathRoch said:

My vendor review relevant to certificates of analysis: ordered 5 times from my current compounder.

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: 99.4% purity, 0.0% total related substances. Clean chromatogram with single sharp peak at expected retention time. Exactly what you want to see.

GenomicsKate said:

One addition: an unstated method makes a report close to uninterpretable.

This answered a question I did not know how to ask. Taking it to my next appointment.

Dr.PathRoch said:

My vendor review relevant to certificates of analysis: ordered 5 times from my current compounder.

I tested my certificates of analysis batch through Janoshik — 99.8% purity. That's within acceptable range for compounded peptides. Turnaround was 8 business days.

The test costs ~$137 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.

Dr.PulmRoch said:

I have a certificate reporting 99.2% purity and 6.1mg content on a vial sold as 5mg, and I cannot work out whether those two numbers are consistent or…

Third-party testing services for certificates of analysis besides Janoshik:

• Janoshik: Gold standard for peptide community, ~$137, 10-14 day turnaround
• Valitech: US-based, ISO 17025 accredited, ~$247
• Eurofins: Full pharmaceutical testing suite, more expensive but comprehensive
• ChemTox: Basic identity and purity testing, ~$117

Janoshik is the community standard but any ISO-accredited analytical lab can verify peptide identity and purity. The key is independence — don't rely solely on the vendor's own testing.

Moderator note: reminder that nothing in this thread is medical advice, and that clinical claims need a source. Tagging this one for the weekly digest.