From the other side of the consultation, briefly.

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

• Janoshik: Gold standard for peptide community, ~$121, 10-14 day turnaround
• Valitech: US-based, ISO 17025 accredited, ~$211
• Eurofins: Full pharmaceutical testing suite, more expensive but comprehensive
• ChemTox: Basic identity and purity testing, ~$121

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.

Dr.RaviCardio said:

Mass spectrometry confirmation for certificates of analysis: beyond HPLC purity, mass spec tells you the molecule's exact molecular weight.

Vendor quality matters when discussing certificates of analysis. I've tested my last 5 batches through Janoshik and purity has ranged from 98.0% 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.

Dr.RaviCardio said:

Mass spectrometry confirmation for certificates of analysis: beyond HPLC purity, mass spec tells you the molecule's exact molecular weight.

This is exactly what I could not find anywhere else.

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

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: 99.2% average across orders (Janoshik verified)
Customer service: Responsive within 6 hours
Price: $138/month for semaglutide 1.7mg equivalent

Moderator note: leaving this open. It is being argued well and the disagreement is the useful part. Carry on.