Dr.EndoEP said:Vendor quality matters when discussing certificates of analysis.
Reconstituted peptide stability data for certificates of analysis: I had Janoshik test my reconstituted vial at day 1, day 14, and day 28 stored in the refrigerator.
Day 1: 100.3% purity
Day 14: 99.0% purity
Day 28: 99.5% purity
Minimal degradation over 28 days when properly refrigerated. This confirms the standard 28-day beyond-use date is appropriate. Beyond 28 days, I'd reconstitute a fresh vial to be safe.
SleepDoc_PDX said:Agreed, and mass spec answers a question purity does not: identity.
That reframing is the part I needed. Printing the relevant bit and taking it with me.
Dr.EndoEP 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.
Sigma-Aldrich — Research-Grade Standards
Certified reference materials, analytical reagents, and research-grade standards for peptide verification. Trusted by laboratories worldwide.
Shop Reference Standardsmona_PHX said:Two reports on the same product from two laboratories, four percentage points apart, and no method stated on either.
I tested my certificates of analysis batch through Janoshik — 99.8% purity. That's within acceptable range for compounded peptides. Turnaround was 10 business days.
The test costs ~$140 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.
Moderator note: the sourcing question belongs in the vendor section and has been split out. Carry on.