Peptide Research Library
A reference hub for laboratory researchers working with synthetic peptides. Below you will find compound guides organised by family, comparison articles, and background on how purity and identity are established. Everything catalogued here is written for research context only.
What research peptides are
Peptides are short chains of amino acids joined by peptide bonds. The line between a peptide and a protein is a matter of convention rather than a hard rule: chains of roughly fifty residues or fewer are generally described as peptides, while longer chains are usually called proteins. Sequence length, amino acid composition, and any modifications to the chain determine a compound’s molecular weight and how it behaves in solution.
The compounds catalogued here are produced by solid-phase peptide synthesis, in which the chain is assembled one residue at a time on an insoluble resin support before being cleaved from that support and purified. The finished material is then lyophilized — freeze-dried under vacuum — which removes water and leaves a dry, stable powder.
Purity and identity are two different questions
Two separate questions matter when assessing a synthetic peptide, and they are frequently conflated. Purity asks what proportion of the material is the intended compound. Identity asks whether the intended compound is what was actually made. A sample can be extremely pure and still be the wrong molecule.
Purity is typically measured by high-performance liquid chromatography (HPLC). The sample is separated into its components and the resulting chromatogram shows each component as a peak. Purity is reported as the area of the target peak expressed as a percentage of total peak area. A figure of 99% or greater indicates that impurities — truncated sequences, deletion products, and residual reagents carried over from synthesis — account for less than one percent of the detected material.
Identity is confirmed by mass spectrometry, which measures the molecular weight of the compound. A measured mass matching the theoretical mass calculated from the published sequence is strong evidence that the correct peptide was synthesised. HPLC on its own cannot establish this.
How to read a certificate of analysis
A certificate of analysis (COA) is the document a laboratory issues to record what testing was performed on a specific batch. A COA worth relying on identifies:
- The batch or lot number. Testing applies to one production run, not to a product line in general. A COA with no batch reference cannot be tied to the vial in front of you.
- The date of testing. A COA is a snapshot of one analysis on one date.
- The testing laboratory. Whether the analysis was performed by the manufacturer or by an independent third party materially changes how much weight it carries.
- The methods used. Commonly HPLC for purity and mass spectrometry for identity.
- The underlying data. The chromatogram and mass spectrum themselves, not only a summary figure typed onto a letterhead.
A COA that reports a purity number without showing the chromatogram it was derived from is difficult to evaluate independently. Our longer treatment of this subject is in the guide to third-party certificates of analysis.
Compound guides by family
Incretin and metabolic peptides
Single- and multi-receptor agonists studied in metabolic research literature.
Mitochondrial-derived peptides
Short sequences encoded in mitochondrial DNA, together with related metabolic cofactors.
- MOTS-c research guide
- Mitochondrial-derived peptides overview
- Browse mitochondrial and metabolic peptides
Structural and repair peptides
Sequences derived from larger endogenous proteins, widely used in tissue and cell research models.
Copper peptides
Copper-binding tripeptide complexes, distinguished by their characteristic blue colouration in solution.
Growth hormone secretagogues
Releasing peptides and analogues that act on the somatotropic axis in research models.
Blends
Multi-compound preparations supplied in a single vial. Full composition is disclosed on every blend product page.
Neuropeptides, bioregulators and melanocortins
Written guides for these families are in preparation. Full specifications and certificates are available on the product listings now.
Comparison guides
Side-by-side treatments of compounds that are frequently confused with one another.
- Retatrutide vs tirzepatide vs semaglutide
- BPC-157 vs TB-500
- Sermorelin vs ipamorelin vs CJC-1295
- GLOW vs KLOW blend
Glossary
- COA — certificate of analysis; the record of testing performed on a specific batch.
- HPLC — high-performance liquid chromatography; the standard method for determining purity.
- Lyophilized — freeze-dried under vacuum, leaving a dry powder.
- Mass spectrometry — measurement of molecular weight, used to confirm identity.
- Residue — a single amino acid unit within a peptide chain.
- Sequence — the order of amino acid residues, conventionally written from the N-terminus to the C-terminus.
- TFA salt — trifluoroacetate counter-ion remaining from HPLC purification; the form in which most synthetic peptides are supplied.
Research use only
All products sold by Santa Cruz Peptides are supplied strictly for laboratory research use. They are not for human or veterinary use, and not for diagnostic or therapeutic purposes. We do not provide dosing, administration or protocol guidance of any kind. Purchasers are responsible for ensuring that material is used only by appropriately qualified personnel in a controlled laboratory setting, and in compliance with all applicable laws and institutional requirements.
Browse the catalog
Every compound is supplied lyophilized at 99%+ purity with a certificate of analysis. View all research peptides.