Good research starts with knowing what you're looking at. This glossary covers the terms you'll run into as you navigate the peptide space - COA documents, lab testing methods, dosing measurements, and the regulatory landscape - defined the way they should have been explained from the start. Clear, honest, and jargon-free.
Peptide A short chain of amino acids - the same building blocks your body uses to make proteins. Peptides are just smaller. Your body makes them naturally, and synthetic versions are lab-made to mimic or influence how those same biological processes work.
Amino acid The individual molecules that link together to form peptides and proteins. There are 20 standard ones. Think of them as letters -peptides are the words they spell.
Synthetic peptide A peptide made in a lab rather than sourced from nature. Most peptides used in research are synthetic, which allows for precise control over what's being studied.
Lyophilized Just a fancy word for freeze-dried. Most research peptides arrive as a fine white powder in a sealed vial — that's the peptide with all the moisture removed. It's stable for storage and needs to be mixed with liquid before use.
Reconstitution Mixing your lyophilized peptide powder with liquid to create a usable solution. Typically done with bacteriostatic water. Getting the volume right matters - it determines the concentration you'll be working with.
Bacteriostatic water (bac water) Sterile water with a small amount of benzyl alcohol added. That alcohol prevents bacteria from growing, which keeps your reconstituted solution stable in the fridge for weeks. It's the standard choice for reconstituting research peptides.
Sterile water Water that's been sterilized to remove contaminants, but without any preservative. Unlike bac water, it won't stop bacteria from growing after you open it - so anything you mix with sterile water should be used right away.
Vial The small sealed glass container peptides are shipped and stored in. The rubber stopper on top lets you draw liquid in or out with a needle without breaking the seal or exposing the contents to air.
GLP-1 (Glucagon-like peptide-1) A hormone your body produces naturally to help regulate blood sugar and appetite. GLP-1 receptor agonists - compounds that mimic or trigger this hormone - have become one of the most widely researched peptide classes, especially around metabolic health.
Research compound (AKA RUO - "Research Use Only") A substance being studied for its potential biological effects that hasn't been approved by regulatory agencies like the FDA for human use. Most peptides fall into this category, which puts them in a legally distinct space from pharmaceutical drugs.
Certificate of Analysis (COA) A document from a laboratory that shows the test results for a specific batch of a compound. A real COA confirms the compound's identity, purity, and concentration. It's the most important quality document you should ask for from any peptide vendor - and if they don't have one, that's your answer.
Third-party testing Testing done by an independent lab with no financial relationship with the vendor. A vendor testing their own products in-house doesn't count. Independence is what makes the result actually mean something.
Purity The percentage of a sample that's actually the compound it's supposed to be, as opposed to leftover byproducts or contaminants from manufacturing. Higher is better. Reputable vendors typically show 98%+ for research-grade peptides.
HPLC (High-Performance Liquid Chromatography) The standard lab method for measuring peptide purity. It separates out the components of a sample so you can see what percentage is actually the peptide versus everything else. If a COA includes an HPLC report, that's a good sign.
Mass spectrometry (MS) A lab technique that identifies a compound by measuring the mass of its molecules. While HPLC tells you how pure something is, mass spec confirms it's actually what it claims to be. The two are often run together — and both showing up on a COA is what you want to see.
Sequence verification Confirmation that a peptide's amino acid sequence matches what it's supposed to be. Especially important for complex peptides - swapping even one amino acid can change how the compound behaves entirely.
Endotoxin testing A test that checks for endotoxins - toxic bacterial byproducts that can trigger serious immune reactions. The most common method is the LAL test. A clean COA should show endotoxin levels below a safe threshold. It's one of the markers worth looking for specifically.
Batch number / Lot number The unique ID assigned to a specific production run of a compound. To verify a COA is legitimate, the batch number on the vial should match the batch number on the COA document. If they don't match, the document isn't relevant to what you actually have.
AxisPharm A U.S.-based analytical lab used by some vendors for third-party testing. Generally considered a credible domestic option with a solid reputation in the community.
Chromate A U.S.-based independent testing lab focused on supplement and research compound analysis. Chromate is particularly known in the community for their COA verification portal - each report comes with a unique job number and access code that lets you confirm the result directly on their site, which makes spotting a doctored or recycled COA straightforward. They also run the Chromate Testing Project, where they conduct unannounced independent testing on products to keep manufacturers honest - no vendor involvement, no heads-up. If you see a Chromate report on a COA, it's one of the easier ones to verify yourself in about 30 seconds.
Freedom Diagnostics Testing A U.S.-based testing laboratory located in Franklin, Tennessee that specializes in purity testing for research peptides. They've grown quickly in the community as a domestic alternative to Janoshik — vendors cite their fast turnaround and clear reporting as standout qualities. Their COAs include a unique accession code that lets you verify the report directly on their website, which is exactly the kind of transparency worth looking for. You'll increasingly see Freedom Diagnostics reports alongside — or instead of — Janoshik reports from vendors who want a U.S.-based option.
Janoshik A commercial testing lab based in the Czech Republic that's become one of the most commonly used third-party testers in the peptide space. Their reports have a recognizable format and can be verified directly on their website — which is one reason they're widely referenced.
Lab report / Test report Sometimes used interchangeably with COA, but there's a subtle difference - the lab report is the raw data from the testing facility, while the COA is the document the vendor issues based on it. Always ask for the actual lab report. A vendor-generated summary without underlying data isn't the same thing.
Vendor A company or individual that sells research peptides. Quality, testing standards, and transparency vary enormously -which is the whole reason this site exists.
White-label vendor A vendor that resells peptides manufactured by someone else, often without disclosing who that is. Not automatically a red flag, but it makes it harder to trace quality back through the supply chain.
API (Active Pharmaceutical Ingredient) The actual active compound - the peptide itself, before it's packaged and sold. Some vendors disclose their API source, meaning they'll tell you who manufactured the raw material. That transparency is generally a good sign.
Independent testing Testing ordered by someone with no financial stake in the outcome - a third-party organization, a researcher, or a community member. The more independent the tester, the more weight the result carries.
Vendor scorecard A quality rating built from aggregated test results, COA consistency, and community feedback over time. PeptideVetter will publish vendor scorecards as part of the platform - so you can see track records, not just snapshots.
Concentration How much of a compound is dissolved in a given volume of liquid, expressed as mg/mL. This is determined when you reconstitute — and it's what tells you how many units to draw for a specific dose.
mg (milligram) One-thousandth of a gram. The standard unit for measuring larger peptide doses.
mcg (microgram) One-thousandth of a milligram. Used for smaller, more precise doses. Worth paying close attention to - confusing mg and mcg is a 1,000x difference, and that's the kind of mistake that matters.
IU (International Unit) A unit that measures biological activity rather than mass. Used for certain peptides and hormones. Not interchangeable with mg or mcg - the conversion is compound-specific, so don't assume.
U-100 insulin syringe The standard syringe for drawing and administering reconstituted peptides. U-100 means it's calibrated for 100 units per mL. Inexpensive, precise, and widely available - the right tool for the job.
Half-life How long it takes for the concentration of a compound in the body to drop by half. This determines how often something needs to be administered to maintain consistent levels - shorter half-life means more frequent dosing.
Titration Starting at a lower dose and working up gradually over time. A common approach when introducing a new compound — lets you gauge response before committing to a higher amount.
Subcutaneous injection An injection into the fatty tissue just under the skin - not into muscle or vein. The most common route of administration for research peptides.
Intramuscular injection (IM) An injection directly into muscle tissue. Less common for peptides than subcutaneous, but used for certain compounds.
FDA (Food and Drug Administration) The U.S. agency that regulates food, drugs, and medical devices. Most research peptides haven't gone through the clinical trial process required for FDA drug approval, which is what puts them in the research compound category rather than the pharmaceutical one.
Not approved for human use The regulatory status that applies to most research peptides. It means the compound hasn't cleared the FDA approval process as a drug. That doesn't tell you much about safety on its own — but it does mean these compounds exist outside the regulated pharmaceutical supply chain, which matters when thinking about quality and sourcing.
Compounding pharmacy A licensed pharmacy that creates customized medications based on a prescription from a licensed physician. Some compounding pharmacies legally produce GLP-1 compounds under FDA oversight - a meaningfully different and more regulated situation than buying from a general research peptide vendor.
503A pharmacy A compounding pharmacy that produces medications for specific individual patients based on a prescription. Regulated at the state pharmacy board level.
503B outsourcing facility A compounding facility registered directly with the FDA that can produce larger batches without patient-specific prescriptions. Subject to federal oversight and cGMP (current Good Manufacturing Practice) standards - a higher regulatory bar than a 503A pharmacy.
Off-label use When an FDA-approved drug is prescribed for a purpose, dosage, or population outside its official approval. Perfectly legal for physicians to do - but it's a completely separate category from research compounds, which haven't been approved at all.
