Clinical perspective, offered as context rather than as advice.

My vendor review relevant to certificates of analysis: ordered 3 times from my current compounder. Consistency has been excellent.

Shipping: Next-day with cold pack
Packaging: Professional, discreet, proper labeling with lot/batch numbers
Purity: 98.0% average across orders (Janoshik verified)
Customer service: Responsive within 2 hours
Price: $120/month for tirzepatide 10mg equivalent

TirzTom said:

Community-verified vendors for certificates of analysis: I maintain a spreadsheet of Janoshik-verified test results submitted by community members.

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

• Janoshik: Gold standard for peptide community, ~$128, 10-14 day turnaround
• Valitech: US-based, ISO 17025 accredited, ~$248
• Eurofins: Full pharmaceutical testing suite, more expensive but comprehensive
• ChemTox: Basic identity and purity testing, ~$118

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.

TirzTom said:

Community-verified vendors for certificates of analysis: I maintain a spreadsheet of Janoshik-verified test results submitted by community members.

Thank you — that is the clearest version of this I have read, and I have read a lot of them.

Adding the clinical framing, because it changes how the question reads.

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.

Moderator note: the sourcing question belongs in the vendor section and has been split out. Tagging this one for the weekly digest.