How to commission independent testing — need advice

DebRD_ATL said:

Third-party testing services for certificates of analysis besides Janoshik: Janoshik: Gold standard for peptide community, ~$126, 10-14 day turnaround…

My HPLC chromatogram analysis for certificates of analysis — I sent my batch to Janoshik and here's what the results showed:

Main peak retention time: 14.7 minutes (consistent with semaglutide reference standard)
Peak purity: 98.0%
Related substances: 0.5% (single impurity at 8.6 minutes — likely a synthesis intermediate)
Mass spec: m/z 4113.58 (matches expected molecular weight)

This is a clean result. The mass spec confirmation is particularly important — it proves the molecule is actually semaglutide and not a substitution.

maria_elpaso said:

Agreed, and mass spec answers a question purity does not: identity.

Saving this. It is the first explanation that did not require me to already understand it. Sending this to two other people who asked me the same thing last week.

DebRD_ATL said:

Third-party testing services for certificates of analysis besides Janoshik: Janoshik: Gold standard for peptide community, ~$126, 10-14 day turnaround…

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: $144/month for tirzepatide 10mg equivalent

jennifer_SEA 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 99.0% 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: reminder that nothing in this thread is medical advice, and that clinical claims need a source. Thread quality here is what the rules are for. Keep it up.