How do you vet a new vendor? My quality checklist

Great matrix. Let me add tirzepatide data since that's increasingly popular:

Tirzepatide is generally harder to compound at high purity because of the more complex peptide structure (39 amino acids vs semaglutide's 31, plus the GIP agonist modification). Any vendor consistently above 97% for tirzepatide is doing well.

The BudgetPeptides number jumps out — 94.2% purity and no COA? That's a red flag. What are the other 5.8%? At those purity levels you could be looking at:

• Degradation products (oxidized semaglutide)
• Truncated peptide fragments from incomplete synthesis
• TFA (trifluoroacetic acid) salt residue from the purification process
• Other unknown impurities

I tried BudgetPeptides once, sent it to Janoshik, got 93.1% purity with a flag for elevated TFA content. TFA at high levels can cause injection site irritation and isn't great for you. Never ordered again.

In this game, the cheapest option is almost never the best value. A $139 vial at 94% purity is worse value than a $249 vial at 99% purity because you're getting ~5% less actual semaglutide AND unknown impurities.

Can we talk about packaging and cold chain differences? This matters more than people think.

My experience across vendors:

• SynthPure: Best packaging I've seen. Custom insulated box, phase-change cold packs (not gel), temperature monitor included, vacuum-sealed vial pouch. Arrives like a pharma product.
• CompoundPharm: Good packaging. Styrofoam insert, gel cold packs, bubble wrap on vials. Professional but not premium.
• PeptideLabs USA: Adequate. Bubble mailer with a single cold pack and some foam padding. Works fine for lyophilized but I wouldn't trust it for liquid.
• BudgetPeptides: Padded envelope. No cold pack. Vial was rattling around loose. The stopper had shifted. Horrifying.
• AmeriPharma: Excellent. Similar to SynthPure quality. They also include a prepaid return label for the cold box, which is a nice touch.

Good additions. Let me also address the COA question since that comes up a lot.

Types of COAs and what they mean:

1. In-house COA: The vendor tested it themselves. Only as trustworthy as the vendor. Can be fabricated easily.
2. Third-party COA (Janoshik): Independent lab in Czech Republic. Gold standard for peptide community. Tests HPLC purity, identity (MS), and sometimes endotoxin. $80-100 per test. Turnaround 5-7 days.
3. Third-party COA (PeptideMeter): Newer lab, Germany-based. Similar methodology to Janoshik. Growing reputation. $75-90 per test. Turnaround 4-6 days.
4. Batch-specific vs generic: A good vendor provides a COA for each batch/lot number. If they show you one COA for all their product, it's meaningless.

My rule: If a vendor provides a Janoshik or PeptideMeter COA with a matching lot number, AND I can verify it with the lab, I'll trust it for a first order. For repeat orders, I'll randomly test every 3rd or 4th purchase.