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Peptide guides and resources

Peptide guides with plain answers to the questions researchers, formulators and buyers ask us most, each one sourced, dated and checked by a named reviewer. No sales pitch, and no advice about using peptides in people or animals.

The law

Are peptides legal in the UK? When a peptide counts as a medicine, why a "research use only" label changes little, which peptides are controlled drugs, and what the MHRA said in 2026, with every source linked.

Research use only, explained What "research use only" and "not for human consumption" mean, who genuinely buys research materials, and how real research supply differs from a sticker on a vial.

The science

What is a peptide? Amino acids, peptide bonds, how sequences are written and read, how peptides are made and tested, and where a peptide ends and a protein begins.

Amino acid codes Every one-letter and three-letter code in one table, including selenocysteine (U) and the ambiguity codes B, Z and X, with a quick self-test.

Certificates and quality

How to read a certificate of analysis What each line on a peptide certificate means, from HPLC purity and mass spectrometry to water, counter-ions and endotoxin, and the signs of a certificate you shouldn't trust.

Peptide purity and net peptide content Why a vial that is 98% pure can still be well under 100% peptide by weight, and how to work out how much peptide you actually have.

In the lab

How to store peptides Storage temperatures for lyophilised powder, keeping moisture and light out, residues that oxidise, solutions, freeze-thaw cycles and dissolving peptides for experiments.

Peptide mass calculator Type a sequence in one-letter code to get its formula, monoisotopic and average mass and the ions you'd expect in a mass spectrum. It opens with our name already typed in.

How these pages are written

  • Sources first. Facts come from regulators, peer-reviewed papers, standard references and manufacturers' technical documents, and each page lists its sources.
  • Dated. The legal explainer shows when it was last reviewed and keeps a record of what changed.
  • What we leave out. No dosing, no reconstitution for use, no effects in people or animals, and no product promotion dressed up as a guide.

Spotted something wrong or out of date? Tell us through our contact page and we'll check it and correct the page.

For how we document the products we supply, see quality and documentation. For who we are, about us.