Source research peptides with confidence.
A practical primer on reading a COA, evaluating suppliers, and avoiding the eight most common procurement mistakes — distilled into 30 pages.
- Read a Certificate of Analysis like a chemist would
- Spot the five red flags that mean "do not buy"
- Storage and reconstitution rules that save you a dead vial
The COA breakdown
Every line on a Certificate of Analysis explained — purity, mass spec, counter-ion, peptide content, endotoxin. With annotated examples.
Supplier evaluation
A 12-minute checklist to evaluate any supplier — including the questions to ask and the answers that mean walk away.
Storage rules
Lyophilized vs reconstituted storage. The mistakes that kill a vial. What bacteriostatic water actually does and when to skip it.
Sample · what you're reading toward
Three COA fields, annotated.
Chapter 2 of the primer walks through every field on a real Certificate of Analysis. Here are three of the most-mistakable, briefly annotated.
Purity by HPLC area at 220 nm (the peptide-bond absorbance wavelength). >99% is the clinical-comparison reference threshold. A purity number with no chromatogram attached is much less trustworthy than a slightly lower number with the trace shown.
Mass-spec identity confirmation. The observed MW should match the theoretical (calculated from sequence) within ~1 Da. Larger drift suggests a synthesis error or contamination. ESI-MS is standard; MALDI-TOF is also acceptable.
Net peptide mass vs gross vial mass. The remaining ~17% is counter-ions (acetate or TFA salt) and water. Critical for concentration-sensitive research — without this figure you can't compute molarity correctly.
The PDF includes a full annotated COA with all 14 lines.
What's inside
9 chapters. 30 pages. No fluff.
After the PDF
Seven emails. One a week-ish. No filler.
The PDF arrives immediately on Day 0. Over the next month you get six follow-up emails. Each one is research-peptide-procurement content, not sales pitch.
- Day 0Welcome + the PDF
The primer arrives in your inbox immediately. No drip — read the whole document on day one if you want.
- Day 2COA reading walkthrough
A worked example: an actual Certificate of Analysis, line by line, with the values that should make you pause.
- Day 5The 12-minute supplier evaluation
The checklist you can run against any supplier site before placing the first order. With the questions that mean walk away.
- Day 9Red flags from real procurement
Specific cases — anonymized — where we found a supplier failing the checklist mid-order. What we did. What the resolution looked like.
- Day 14Storage and reconstitution gotchas
The mistakes that kill a vial after it arrives. The bacteriostatic-water math. Why "shake to dissolve" is almost always the wrong instruction.
- Day 21Counter-ions and assay compatibility
When TFA salt is a problem. When acetate is worth paying for. How net-peptide-content errors break concentration-sensitive work.
- Day 30When to escalate. When to walk.
The conversation patterns with supplier support that predict whether a relationship will scale or break under real volume.
Unsubscribe link in every email. After Day 30, occasional notes only — typically monthly or less.
Most "research peptide" content on the open web is written under a fabricated persona — a fictional "Dr. someone" with invented credentials. The Sourcing Primer is a team-edited publication. No single author claims the work. No fabricated medical authority is invoked to lend the document credibility it has to earn from the writing itself.
- Research the published peer-reviewed literature on each topic covered
- Verify supplier practices through direct procurement orders and COA evaluation
- Cross-check claims internally before publication
- Update content when supplier practices change or new research is published
Why this exists
Sourcing well doesn't take a chemistry degree.
It takes about an hour of focused reading to learn what separates a real supplier from a marketing site. This primer compresses that hour into 30 pages.
It's the document we wanted when we started — published by The Sourcing Primer Editorial Team. No fluff, no sales pitch, no medical claims.
Common questions
Before you opt in.
- Is the PDF actually free?
- Yes. The primer is free in exchange for your email. We use the email to send the primer, follow-up reference content, and occasional notes about suppliers we recommend. Unsubscribe in one click any time.
- Will I get spammed?
- No. You'll get a welcome email with the PDF, then 6 follow-up emails over the next month with practical research-peptide content. After that, occasional notes — usually monthly or less. Unsubscribe links are in every email.
- Does this give dosing advice?
- No. The Sourcing Primer is for laboratory and educational research reference. The compounds discussed are not approved for human consumption. We do not recommend doses, administration routes, or therapeutic use. For medical questions, consult a licensed physician.
If you want more
Three related notes from the wider network.
Molecular Notes is an editorial publication covering the chemistry side of research peptides. These three articles complement the primer.
Get the primer.
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Note: The primer is intended for laboratory and educational research use. Compounds discussed are not approved for human consumption. The Sourcing Primer Editorial Team does not provide medical advice.