Peptide Glossary
Plain-language definitions for the terms that show up across our product pages, protocols, and blog — reconstitution, testing methodology, storage, and more.
Bacteriostatic Water (BAC Water)
Sterile water containing 0.9% benzyl alcohol, used to reconstitute lyophilized peptide powder.
Bacteriostatic water is sterile water for injection that contains 0.9% benzyl alcohol as a preservative. The benzyl alcohol inhibits bacterial growth, which is why bacteriostatic water can be used to reconstitute a vial and then drawn from multiple times over a period of weeks, unlike plain sterile water which is meant for single use.
It's added slowly to a lyophilized peptide vial — usually run down the inside wall of the vial rather than injected directly onto the powder — to avoid excess foaming or agitation that can degrade the peptide structure.
Reconstitution
The process of dissolving lyophilized (freeze-dried) peptide powder into a liquid solution before use.
Peptides typically ship as a lyophilized powder for stability. Reconstitution is the process of adding a solvent — most often bacteriostatic water — to bring the peptide back into solution at a known concentration (mg/mL), so it can be measured and drawn accurately with a syringe.
The volume of solvent added determines the final concentration: a 5mg vial reconstituted with 1mL of water yields a 5mg/mL solution, while the same vial reconstituted with 2mL yields 2.5mg/mL. Getting this number right is the basis of every dosing calculation.
Lyophilized Powder
Freeze-dried peptide with the water content removed, used for long-term stability during storage and shipping.
Lyophilization (freeze-drying) removes water from a peptide solution under vacuum at low temperature, leaving a stable powder. Peptides in this form resist degradation far better than peptides already in solution, which is why virtually all research peptides are sold lyophilized rather than pre-mixed.
A lyophilized peptide is stable at refrigerated or frozen temperatures for extended periods. Once reconstituted into solution, that stability window shortens considerably — which is why unreconstituted vials and reconstituted vials have different storage guidance.
HPLC-MS Testing
High-Performance Liquid Chromatography paired with Mass Spectrometry — the analytical method used to verify a peptide's identity and purity.
HPLC (High-Performance Liquid Chromatography) separates a sample into its individual components based on how they interact with a chromatography column, producing a chromatogram that shows purity as the percentage of the total signal belonging to the intended peptide peak.
MS (Mass Spectrometry) measures the molecular weight of separated components, confirming that the primary peak actually is the peptide it's supposed to be, not just a similarly-behaving impurity. Used together, HPLC-MS verifies both identity (is this actually the right compound) and purity (how much of the vial is that compound versus everything else).
Certificate of Analysis (CoA)
The lab report for a specific batch, showing its measured purity and identity test results.
A Certificate of Analysis is a document from an independent testing laboratory reporting the results of specific tests — typically HPLC purity and mass spec identity confirmation — for a specific manufacturing batch, referenced by a batch or lot number.
A CoA is batch-specific, not product-generic: it tells you what a lab found in that particular batch, not what the supplier claims about the product in general. Checking that the batch number on your CoA matches the batch number on your vial is the only way to confirm the two actually correspond.
Purity Percentage
The proportion of a vial's contents that is the intended peptide, as measured by HPLC — not a measure of safety or effectiveness.
Purity percentage, as reported on a Certificate of Analysis, reflects the proportion of the HPLC chromatogram's total peak area attributable to the intended peptide, versus related impurities, degradation products, or synthesis byproducts.
A 99% purity result means roughly 1% of the measured signal comes from something other than the target peptide — commonly truncated sequences or oxidation products from the synthesis process. Purity is an analytical measurement of composition, not a claim about safety or biological effect.
Subcutaneous (SC) vs Intramuscular (IM) Injection
Two injection routes — SC deposits into the fat layer under the skin, IM deposits into muscle tissue — with different absorption profiles.
Subcutaneous (SC) injection deposits solution into the layer of fat just beneath the skin, typically using a short, fine-gauge needle (commonly the same insulin syringe used for reconstituted peptide dosing). Absorption from SC tissue is generally slower and more gradual than IM.
Intramuscular (IM) injection deposits solution directly into muscle tissue, which has a richer blood supply and can lead to faster absorption for some compounds. Most peptide research protocols specify SC administration by default; IM is used where a specific protocol calls for it.
Half-Life
The time it takes for half of an administered dose to be cleared from the body — a key factor in how often a compound needs to be dosed.
A peptide's half-life is the time required for its concentration in the body to fall by 50%. Shorter half-lives generally require more frequent dosing to maintain stable levels; longer half-lives allow for less frequent administration.
Half-life varies enormously between peptides — from roughly 1–4 hours for a peptide like BPC-157 to several days for a modified, longer-acting compound. It's one of the main reasons dosing frequency differs so much from one research protocol to the next.
Cold Chain / Storage Temperature
The temperature-controlled handling a peptide needs from shipping through storage, to prevent degradation.
Peptides are proteins, and like most proteins, their structure can degrade with heat exposure, agitation, or time in solution. "Cold chain" refers to keeping a product within its required temperature range continuously — during shipping, and then in storage once it arrives.
As a general pattern: unreconstituted lyophilized powder is more heat-stable and can typically tolerate brief transit at room temperature, while long-term storage calls for freezer temperatures (commonly -20°C). Once reconstituted into solution, refrigeration (2-8°C) and prompt use become far more important, and repeated freeze-thaw cycles should be avoided.
Research Use Only (RUO)
A labeling designation meaning a compound is sold for laboratory and research purposes, not for human or animal consumption.
"Research Use Only" (RUO) is a standard designation for compounds that have not been evaluated or approved by a regulatory body — such as Health Canada or the FDA — for human or veterinary use. RUO products are intended for in vitro or laboratory research settings only.
This designation is distinct from a compound simply lacking approval for a specific indication (many approved drugs are also studied for off-label uses). RUO means the product itself, as sold, has not been evaluated for human consumption, dosing safety, or clinical use of any kind.
Research use only. Definitions above describe general laboratory and pharmacological concepts for research education purposes. They are not medical advice and do not describe or endorse human use of any product sold by JA Performance.