Glossary
Technical terms from certificates of analysis and product specifications, briefly explained.
You will come across these terms on a certificate of analysis, a label, or a product page. Each explanation is kept short; the articles in the knowledge base go into more depth.
Analysis and quality
COA
Certificate of analysis. A document from a laboratory with the test results of a single batch: which compound, which method, which result, and on what date.
HPLC
High-performance liquid chromatography. A technique that separates the components of a sample, so that you can measure what share of it is the intended compound. The result is a chromatogram with peaks.
Chromatogram
The graph produced by an HPLC measurement. Each peak represents a component. The main peak is the intended compound; smaller peaks are impurities.
Retention time
The time a compound takes to pass through the HPLC column. Under the same measurement conditions, this time is always the same for a given compound, which helps to identify it.
Purity
The area of the main peak as a percentage of all peaks in the chromatogram. A purity of 99% means that 99% of the measured signal comes from the intended compound. It says nothing about how much of the compound is in the vial.
Mass spectrometry
A technique that measures the mass of molecules, often abbreviated to MS. If the measured mass matches the calculated mass of the compound, its identity is confirmed.
Molecular mass
The mass of a single molecule, expressed in grams per mole or in daltons. For a peptide, the mass follows directly from the amino acid sequence.
Peptide content
The part of the powder that is actually peptide. The rest consists of counterions and bound water. Peptide content is therefore always below 100%, even at high purity.
Counterion
A charged particle that balances the charge of the peptide, for example acetate or trifluoroacetate (TFA). The counterion comes from the purification and counts toward the weight of the powder.
Endotoxin
A component of the cell wall of certain bacteria. In cell culture, endotoxin can interfere with measurement results. An endotoxin test measures how much of it a sample contains.
Reference standard
A substance of known composition and purity, used to calibrate a measurement method or to compare an unknown sample against.
Product and packaging
Batch
A single production run of a compound. All vials from the same batch were made at the same time and under the same conditions, and share one certificate of analysis.
Batch number
The number that identifies a batch. It appears on the label of every vial and on the certificate. Use the batch number to look up the correct COA.
Lyophilization
Freeze-drying. A solution is frozen, after which the ice vaporizes under vacuum. What remains is a dry powder that stays stable much longer than the solution.
Peptide
A chain of amino acids, shorter than a protein. There is no fixed boundary, but chains of up to a few dozen amino acids are usually called peptides.
Amino acid
The building block of peptides and proteins. There are twenty standard amino acids, each with its own three-letter and one-letter abbreviation.
Sequence
The order of the amino acids in a peptide, written from the start (N-terminus) to the end (C-terminus).
CAS number
A unique registry number for a chemical substance, assigned by the Chemical Abstracts Service. It prevents confusion between substances that have several names.
Bacteriostatic water
Sterile water to which 0.9% benzyl alcohol has been added. The benzyl alcohol inhibits the growth of bacteria in a vial once it has been opened.
Rules and ordering
RUO
Research Use Only. A product with this designation is for laboratory research use only. It is not a medicine and must not be administered to humans or animals.
In vitro
Literally: in glass. Research outside a living organism, for example in a test tube or in cell culture.
VIES
The European Commission system for checking whether the VAT number of a business in the EU is valid. We use it when reviewing applications for a business account.