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: 99.2% purity, 0.2% total related substances. Clean chromatogram with single sharp peak at expected retention time. Exactly what you want to see.

Dr.SportsMedIN said:

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

Thank you — that is the clearest version of this I have read, and I have read a lot of them. Printing the relevant bit and taking it with me.

Dr.PathRoch said:

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

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

• Janoshik: Gold standard for peptide community, ~$142, 10-14 day turnaround
• Valitech: US-based, ISO 17025 accredited, ~$242
• Eurofins: Full pharmaceutical testing suite, more expensive but comprehensive
• ChemTox: Basic identity and purity testing, ~$112

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.

HealthEcon_DC said:

Two reports on the same product from two laboratories, four percentage points apart, and no method stated on either.

Vendor quality matters when discussing certificates of analysis. I've tested my last 5 batches through Janoshik and purity has ranged from 98.2% to 99.2%. 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.

Moderator note: good thread. Keeping it here rather than moving it, because the question is general enough to be useful. Tagging this one for the weekly digest.