TinaHashiRN said:My vendor review relevant to certificates of analysis: ordered 3 times from my current compounder.
Community-verified vendors for certificates of analysis: I maintain a spreadsheet of Janoshik-verified test results submitted by community members. Across 45 submitted tests:
- 78% tested at ≥98% purity
- 15% tested at 95-98% purity
- 7% tested at <95% purity (concerning)
The vendors with consistently high purity results are listed in the Vendor Directory. We update monthly based on new community submissions.
Admin said:One addition: an unstated method makes a report close to uninterpretable.
Thank you — that is the clearest version of this I have read, and I have read a lot of them. Taking it to my next appointment.
TinaHashiRN said:My vendor review relevant to certificates of analysis: ordered 3 times from my current compounder.
HPLC results interpretation for certificates of analysis: when you get your Janoshik report back, here's what the numbers mean:
- Purity %: Should be >97%. Below 95% is concerning.
- Retention time: Should match reference standard for the peptide
- Related substances: Degradation products should be <2% total
- Single impurity: No individual impurity should exceed 1%
My last batch: 99.3% purity, 0.1% total related substances. Clean chromatogram with single sharp peak at expected retention time. Exactly what you want to see.
Sigma-Aldrich — Research-Grade Standards
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Shop Reference StandardsDr.AddMedPHL said:Two reports on the same product from two laboratories, four percentage points apart, and no method stated on either.
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: 100.1% purity
Day 14: 99.0% purity
Day 28: 98.1% 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.
Moderator note: the sourcing question belongs in the vendor section and has been split out. Thread quality here is what the rules are for. Keep it up.