Research peptide glossary for wholesale buyers

A plain-English research peptide glossary for the terms that come up when you order wholesale: chemistry and testing vocabulary, packaging and storage terms, and ordering terms on a pro-forma invoice.

Peptide glossary: chemistry and testing terms

Acetate salt — a peptide supplied with acetate (acetic acid) as its counter-ion rather than TFA. Acetate is generally considered a milder counter-ion for research use, though both are standard forms peptides are supplied in.

Amino acid sequence — the order of amino acids that make up a peptide's chain, which defines the molecule. Two products with different names can share part of a sequence when one is an analog or fragment of the other.

CAS number — a unique registry number assigned to a specific chemical substance by the Chemical Abstracts Service, used to confirm that two listings referring to the same compound by different names are in fact identical. See our molecular weight and CAS reference for the compounds in our catalog.

Counter-ion — the ion paired with a peptide in its salt form, left over from synthesis. TFA and acetate are the two counter-ions most commonly seen in research peptides, and a counter-ion adds weight to a lyophilized vial without adding peptide.

HPLC — high-performance liquid chromatography, the standard method for measuring peptide purity. The result is typically reported as a percentage of area under the main peak in a chromatogram, alongside the peak's retention time.

Mass spectrometry — an analytical method that measures the mass of a molecule, used on a peptide lot to confirm identity by comparing the observed mass against the theoretical mass calculated from its sequence or structure.

Molecular weight — the mass of one molecule of a compound, usually expressed in daltons, calculated from its chemical structure. It is one of the values a mass spectrometry result is checked against.

Net peptide content — the proportion of a vial's labeled weight that is actual peptide, once the counter-ion and residual moisture from lyophilization are accounted for. It is reported separately from purity, which measures how clean the main peak is rather than how much of the vial is peptide.

Peptide blend — two or more peptides combined and lyophilized into a single vial, sold as one SKU rather than as separate products mixed by the buyer.

Research solution — a peptide already dissolved for use rather than supplied as a lyophilized powder, such as the products in our Spray format line. A peptide in solution is generally considered less stable over time than the same peptide in its lyophilized form.

Retention time — how long a compound takes to travel through an HPLC column before it is detected, reported alongside the purity percentage on a chromatogram. It is useful for comparing one lot of a product against another lot of the same product.

TFA salt — a peptide supplied with trifluoroacetic acid (TFA) as its counter-ion, one of the two counter-ions most commonly seen in synthetic research peptides.

Packaging and storage

Acetic acid water — a dilute acetic acid solution used as a diluent for certain peptides in research settings that call for an acidic aqueous solution rather than a neutral one. Sold by the kit in our Lab supplies category.

Bacteriostatic water — sterile water containing 0.9% benzyl alcohol as a bacteriostatic preservative, supplied in a multi-use vial so it supports repeated access over a vial's working life. See our bacteriostatic water guide for how it differs from sterile and acetic acid water.

COA — certificate of analysis, the lab report for one specific lot covering identity, purity, net content and appearance. Our guide to reading a peptide COA covers each field.

Cold chain — temperature-controlled shipping and storage used for material that must stay within a narrow temperature range from origin to destination. Sealed lyophilized peptide kits do not require cold-chain shipping; they ship at ambient temperature and are stable for the transit window.

Desiccant — a drying agent packed alongside lyophilized material to keep ambient moisture away from the cake during storage, included in outer packaging where provided.

Kit — the unit of sale on this site: a sealed carton of 10 vials, one compound and one size per kit. Kits of different compounds and sizes mix freely on one order.

Lot — a single production batch of a product, tied to one certificate of analysis. The lot number appears on both the carton and the COA packed inside it.

Lyophilization — the freeze-drying process that removes water from a peptide solution under vacuum, leaving a stable dried cake. It is the standard form most research peptides are supplied in.

Lyophilized cake — the dried, porous solid left in a vial after lyophilization. It is hygroscopic, meaning it draws moisture from the air if the vial seal is broken and left open.

Ordering and freight

Freight — the cost of shipping an order, quoted on the pro-forma invoice once an order sheet is submitted. Orders ship from a US warehouse by FedEx, the same business day when released by noon Central.

MOQ — minimum order quantity. Our MOQ is 50 kits per order, reached by mixing any combination of compounds and sizes.

Pro-forma invoice — the invoice sent back by email after a purchase order is submitted, listing the kits ordered, the price per kit at the applicable tier, freight, and payment instructions. An order releases to the warehouse once the pro-forma is paid and funds clear.

RUO — research use only, the condition every product on this site is sold under: for laboratory research, not for human or animal use, and not for resale under any other claim.

SKU — stock-keeping unit, an individual size of a product. A single compound can have several SKUs, one per size offered.

Tier — the pricing level an order qualifies for, based on the total number of kits on that order. Standard pricing applies from 50 to 99 kits; Volume pricing, the lowest listed price per kit, applies at 100 kits and up. Orders of 500 kits or more are priced by custom quote instead of a listed tier.

Wire transfer — a bank-to-bank payment, one of the two payment methods accepted on this site, alongside cryptocurrency. An order releases to the warehouse once payment clears.

For laboratory research use only. Not for human or animal consumption.

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