Listings and certificates for research peptides use a mix of chemistry, laboratory and shipping vocabulary. This glossary gives short, neutral definitions of the terms you are most likely to meet when comparing the UK brands on this marketplace, from salt forms and test methods to escrow and dispatch. It describes what each word means, not whether any product meets it. For how tests fit together, see Testing 101; to browse listings, see compounds and brands.
A
- Acetate salt
- A form of a peptide in which acetate is the counter-ion. It is usually produced by an ion exchange step after HPLC purification, replacing trifluoroacetate. See residual solvents and counter-ions.
- Acetonitrile
- An organic solvent used with water as the mobile phase in HPLC purification. Traces left after drying are reported in ppm as a residual solvent.
- Amino acid sequence
- The order of amino acids that makes up a peptide, written from the amino end to the carboxyl end using one-letter or three-letter codes. Two products with the same name should share the same sequence.
- API
- Active pharmaceutical ingredient. The term is borrowed from medicines manufacturing and, on listings, normally refers to the bulk compound before it is filled into vials.
- Assay
- Any laboratory test that measures a property of a sample. On a certificate it often means the test that measures how much compound is present.
B
- BAC water
- Bacteriostatic water: sterile water containing a small amount of benzyl alcohol. Some brands list it as a separate supply item alongside peptides. This marketplace gives no instructions for its use.
- Batch or lot number
- A code that identifies one production run. It should appear on the vial label and on the certificate, and it is the only reliable way to link the two.
- Blind sample
- A sample sent to a laboratory without the brand knowing it will be tested, often bought by a customer or group. It reduces the chance of a specially prepared sample being tested.
C
- CAS number
- A unique registry number assigned to a chemical substance by the Chemical Abstracts Service. It helps identify a compound regardless of trade or common names, though not every research peptide has one.
- Certificate of analysis (CoA)
- A laboratory report giving test results for a named batch, such as purity, identity and quantity. See our certificate guide.
- Chromatogram
- The graph produced by HPLC or gas chromatography, showing detector response over time. Each peak represents a separated component of the sample.
- Counter-ion
- A charged ion that balances the charge on a peptide, such as trifluoroacetate, acetate or chloride. It adds to the weight of the powder in a vial.
- Crimp seal
- The aluminium band rolled under the lip of a vial to hold the rubber stopper in place. A lifted or split crimp is a recognised transit fault.
- Crypto payment
- Payment in a cryptocurrency. On this marketplace, crypto payments go into escrow rather than directly to the brand.
D
- Deletion sequence
- An impurity in which one or more amino acids are missing from the intended chain, usually from an incomplete coupling step during synthesis. It shows up as a separate peak on HPLC.
- Dispatch
- The point at which a brand hands an order to Royal Mail or a courier. Brands listed here dispatch from inside the UK. See UK peptide delivery.
E
- Endotoxin
- A component of the outer membrane of certain bacteria that can contaminate materials during manufacture. Results are reported in endotoxin units (EU) per mg, usually measured with the LAL test.
- Escrow
- An arrangement in which payment is held by a third party until agreed conditions are met. Here, the brand is paid only after delivery. See how escrow works.
- Expiry date
- The date after which the manufacturer no longer supports the stated specification. Some labels show a retest date instead.
F
- Fill amount
- The quantity of material placed into each vial, normally stated as mg. It refers to the solid weighed in, which includes any counter-ion and water.
- Fmoc
- A protecting group (fluorenylmethyloxycarbonyl) used in solid-phase peptide synthesis to shield the amino end of each amino acid until the next coupling.
G
- Gas chromatography (GC)
- A technique that separates volatile substances in a gas stream. Headspace GC is the usual method for measuring residual solvents.
- GBP price per mg
- The listed price in pounds sterling divided by the stated milligrams per vial or kit. It allows like-for-like comparison of list prices across brands and pack sizes, not of quality.
H
- HPLC
- High-performance liquid chromatography. It separates the components of a sample, and the share of the main peak is reported as HPLC purity.
- Hydrochloride salt
- A peptide form with chloride as the counter-ion, produced by exchange with hydrochloric acid.
I
- ICH Q3C
- An international guideline for medicines that classes residual solvents into three groups with concentration limits. It is often quoted as a reference point for research materials.
- Identity test
- A test that checks whether the compound is what the label says, usually mass spectrometry comparing the measured mass with the expected one.
- Impurity
- Any component other than the target compound, such as deletion sequences, oxidised forms or residual solvents.
J
- Janoshik
- An independent analytical laboratory whose reports are often attached to research peptide listings. Its reports can be looked up on its own website using a report code.
K
- Karl Fischer titration
- A method for measuring water content in a sample. It contributes to the calculation of net peptide content.
- Kit
- A pack containing several vials of the same compound and strength. The number of vials varies by brand, so check each listing.
L
- LAL
- Limulus amebocyte lysate. A reagent taken from horseshoe crab blood cells and used to detect and measure bacterial endotoxin.
- Listing
- A product page showing one brand’s offer for a compound, with strength, price in GBP and any documents the brand has supplied.
- Lyophilised
- Freeze-dried. Water is removed by freezing and then lowering the pressure, leaving a dry solid. See checking a lyophilised vial.
M
- Mass spectrometry (MS)
- A technique that measures the mass of molecules. On a certificate it is the usual identity test for a peptide.
- MHRA
- The Medicines and Healthcare products Regulatory Agency, the UK regulator for medicines and medical devices. A research use only label does not by itself decide whether a product is treated as a medicine.
- Milligram (mg)
- The unit used for peptide strength on labels. One milligram is one thousandth of a gram.
- Molecular weight
- The mass of one molecule of a compound, given in daltons (Da) or grams per mole. Mass spectrometry compares the measured value with this figure.
N
- Net peptide content
- The share of the vial’s solid that is actually peptide, once counter-ions and water are accounted for. It is a separate figure from HPLC purity.
- NMR
- Nuclear magnetic resonance spectroscopy. It identifies molecules from the behaviour of atomic nuclei in a magnetic field, and 19F NMR is used to measure TFA.
P
- Peak area
- The area under a peak on a chromatogram. HPLC purity is calculated from the main peak’s area as a share of all peaks detected.
- Peptide
- A short chain of amino acids joined by peptide bonds. Chains of roughly 50 amino acids or more are usually called proteins.
- Purity
- A test measure, usually from HPLC, giving the percentage of detected material that is the target compound. It does not account for solvents, counter-ions or water.
Q
- Quantity test
- A test that measures how many milligrams of compound are in a vial, for comparison with the label strength.
R
- Research use only
- A label stating that a product is supplied for laboratory research and not for human or veterinary use. It describes the seller’s stated purpose rather than a test result.
- Residual solvent
- A trace of organic solvent left from manufacture, reported in ppm. See residual solvents and counter-ions.
- Retention time
- The time a component takes to pass through a chromatography column. It is used to identify peaks against reference standards.
S
- Salt form
- The counter-ion a peptide is supplied with, such as TFA, acetate or hydrochloride. It affects the weight of the powder.
- SPPS
- Solid-phase peptide synthesis, the standard method of building a peptide one amino acid at a time on a resin support.
- Stopper
- The rubber plug that seals a vial, held in place by the crimp seal.
T
- TFA
- Trifluoroacetic acid. It is used to cleave peptides from resin and in HPLC, and it often remains as a trifluoroacetate counter-ion.
- Third-party testing
- Testing carried out by a laboratory independent of the brand. A certificate should name the laboratory so this can be checked.
- Tracking number
- The reference issued by Royal Mail or a courier at dispatch, used to follow a parcel and to support an escrow claim if it goes missing.
U
- UK dispatch
- Shipping that starts from an address inside the United Kingdom, so the parcel does not pass through UK customs.
V
- Vial
- The small sealed glass container holding a freeze-dried peptide, closed with a stopper, crimp and flip-off cap.
W
- Water content
- The amount of water in a freeze-dried solid, usually measured by Karl Fischer titration and reported as a percentage.
If a term on a listing or certificate is missing from this list, ask the brand to explain it before ordering. Payments are held until delivery under the escrow refund policy.