Dr.PainCLE said:

The provenance questions are more useful than the numbers.

Thank you — that is the clearest version of this I have read, and I have read a lot of them. Sending this to two other people who asked me the same thing last week.

From the other side of the consultation, briefly.

My vendor review relevant to certificates of analysis: ordered 4 times from my current compounder. Consistency has been excellent.

Shipping: 2-day priority with gel ice
Packaging: Professional, discreet, proper labeling with lot/batch numbers
Purity: 97.1% average across orders (Janoshik verified)
Customer service: Responsive within 4 hours
Price: $137/month for semaglutide 2.4mg equivalent

Dr.NephBHM_UK said:

They are not contradictory, they measure different things, and this is the single most common misreading of a certificate.

Community-verified vendors for certificates of analysis: I maintain a spreadsheet of Janoshik-verified test results submitted by community members. Across 55 submitted tests:

• 75% tested at ≥98% purity
• 18% tested at 95-98% purity
• 7% tested at <95% purity (concerning)

The vendors with consistently high purity results are listed in the Vendor Directory. We update monthly based on new community submissions.

COA_Karl said:

How to read a Certificate of Analysis — complete guide Posting this as an important update for the coa & analytical testing community.

Reconstituted peptide stability data for certificates of analysis: I had Janoshik test my reconstituted vial at day 1, day 14, and day 28 stored in the refrigerator.

Day 1: 99.0% purity
Day 14: 98.2% purity
Day 28: 98.4% purity

Minimal degradation over 28 days when properly refrigerated. This confirms the standard 28-day beyond-use date is appropriate. Beyond 28 days, I'd reconstitute a fresh vial to be safe.

Moderator note: reminder that nothing in this thread is medical advice, and that clinical claims need a source. No action needed from anybody.