Research peptide guides
Plain-language explainers on peptide chemistry, lab paperwork and the regulatory backdrop. Each one is meant to be read before you buy anything.
These guides explain the documents and terms that vendor pages rely on. They are educational and describe no results for the body. For dated comparisons and vendor walkthroughs, see the blog. For how we score vendors, see our methodology.
Foundations
What a peptide is, in plain language
A peptide is a short chain of amino acids joined end to end by peptide bonds. That definition covers hormones your body makes on its own and synthetic compounds made in a lab for research, which is most of what a site like this one reviews.
GLP-1, GIP and glucagon agonists: what “dual” and “triple” mean
“Dual” and “triple” agonist describe how many different hormone receptors a peptide activates at once. It's the single most useful distinction for understanding why tirzepatide, semaglutide and retatrutide keep getting mentioned in the same breath, and why they aren't interchangeable.
Reading documents
How to read a certificate of analysis
A certificate of analysis, or COA, is a lab's written report of what it measured on one specific batch. It isn't a guarantee, and it isn't the manufacturer's own marketing claim. It's only as reliable as the lab that signed it and the batch it actually covers.
HPLC purity and mass spectrometry: what each one shows
HPLC and mass spectrometry answer two different questions. HPLC asks how much of what's in the vial is the thing you ordered. Mass spectrometry asks whether that thing has the right structure at all. A certificate that only runs one of them has only answered half the question.
How to spot a fake or copy-pasted certificate of analysis
A certificate of analysis is just a PDF or a photo. Nothing stops a vendor from reusing one, editing one, or posting a certificate for a different batch than the one they're shipping. None of the red flags below prove fraud on their own, but each one is a reason to ask more questions before trusting the number.
Regulation
What research-use-only labeling does and does not mean
"Research Use Only" is printed on almost everything these sites sell. It doesn't mean what a lot of buyers assume, and the FDA has said so directly, in writing, more than once in 2025 and 2026.
Handling
Storing lyophilized peptides: the research handling basics
Freeze-dried, or lyophilized, peptide loses its integrity in fairly predictable ways: heat, light, repeated freeze-thaw cycles, and contamination from non-sterile handling. Most storage guidance is really about controlling those four things. This page describes how suppliers commonly instruct handling of the substance itself. It is not instructions for using a peptide on yourself.