TrialNerd_Beth said:

I tested my certificates of analysis batch through Janoshik — 99.8% purity.

Mass spectrometry confirmation for certificates of analysis: beyond HPLC purity, mass spec tells you the molecule's exact molecular weight. This confirms identity — not just purity.

Why this matters: HPLC can show you a "pure" compound, but if it's pure of the WRONG compound, purity is meaningless. Mass spec at m/z 4113.58 Da confirms it's actually semaglutide. My Janoshik report includes both HPLC and mass spec.

If your testing provider only offers HPLC, consider upgrading to include mass spec for at least your first batch from a new vendor.

WendyG_ATL said:

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

That reframing is the part I needed. Printing the relevant bit and taking it with me.

TrialNerd_Beth said:

I tested my certificates of analysis batch through Janoshik — 99.8% purity.

Vendor quality matters when discussing certificates of analysis. I've tested my last 6 batches through Janoshik and purity has ranged from 98.9% to 100.3%. 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.

JennaRN said:

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

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

Shipping: Same-day local pickup
Packaging: Professional, discreet, proper labeling with lot/batch numbers
Purity: 97.6% average across orders (Janoshik verified)
Customer service: Responsive within 6 hours
Price: $158/month for semaglutide 2.4mg equivalent

Moderator note: a post naming a supplier has been edited. Discuss suppliers in the review sections, not here.