Understanding peptide purity percentages — what worked for you?

steve_okc said:

Vendor quality matters when discussing certificates of analysis.

This matches mine closely enough to be worth saying so out loud.

steve_okc said:

Vendor quality matters when discussing certificates of analysis.

I tested my certificates of analysis batch through Janoshik — 98.1% purity. That's within acceptable range for compounded peptides. Turnaround was 12 business days.

The test costs ~$127 but gives you actual HPLC chromatography data plus mass spec confirmation. For the peace of mind alone, it's worth every penny. I test every new batch from a new vendor.

steve_okc said:

Vendor quality matters when discussing certificates of analysis.

COA red flags for certificates of analysis — here's what to look for when reviewing a Certificate of Analysis:

• No HPLC data: If there's no chromatography graph, it's not a real COA
• Exact 100% purity: Suspicious — real testing always shows slight variation
• No batch number: Can't trace back to specific production
• No endotoxin testing: For injectables, this is essential
• Template looks like it was made in Word: Professional labs have standardized formats

I have seen fake COAs that are literally photoshopped. Always verify independently if possible.

Following on from steve_okc — and this may be the naive question:

How long did you give it before you decided it was working?

labquiet_amy said:

COA red flags for certificates of analysis — here's what to look for when reviewing a Certificate of Analysis: No HPLC data: If there's no…

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: 99.6% average across orders (Janoshik verified)
Customer service: Responsive within 6 hours
Price: $158/month for semaglutide 1.7mg equivalent