Glossary of peptide terms
Each term you are likely to meet on a certificate or product page, explained in a sentence or two.
- What does aliquot mean?
- What is a cold chain?
- What counts as bacteriostatic water?
- What does HPLC stand for?
- What does endotoxin mean?
- What is mass spectrometry used for?
- What does lyophilisation mean?
- What does quality control testing involve?
- What does purity mean on a peptide label?
- What is meant by a triple agonist?
What does aliquot mean?
A measured portion taken from a larger sample. When reconstituted material is split into single-use aliquots, each one is frozen and thawed just once. That protects the batch from the damage repeated freeze-thaw cycles cause.
What is a cold chain?
Temperature-controlled storage and transport with no gaps, all the way from producer to end user. Every gap adds heat exposure. The damage adds up and never resets, so what counts is the total time spent outside the safe range.
What counts as bacteriostatic water?
Sterile water with about 0.9% benzyl alcohol. The benzyl alcohol is a preservative that slows bacterial growth. It is the reason a vial can be entered several times without bacteria multiplying inside.
Read more: bacteriostatic water compared with sterile water →
What does HPLC stand for?
High-performance liquid chromatography. It separates the parts of a mixture by forcing it under pressure through a packed column. Comparing the peak areas gives the purity figure printed on a certificate.
What does endotoxin mean?
A piece of bacterial cell wall that survives sterilisation. It can disturb biological assays even when no live organism is left. That is why endotoxin results are reported apart from sterility results.
What is mass spectrometry used for?
It turns a sample into ions and measures their mass-to-charge ratio. For peptides it answers one question: is this the right molecule? It checks whether the measured mass agrees with the mass predicted from the planned sequence.
What does lyophilisation mean?
Another word for freeze-drying. Water leaves a frozen sample under vacuum by turning straight from ice to vapour. What remains is a dry, porous solid that is much more stable than the same material dissolved.
What does quality control testing involve?
The checks a batch goes through before release: identity, purity and appearance, plus sterility and endotoxin where relevant. Results are logged against a lot number, so each vial can be traced to its own data.
What does purity mean on a peptide label?
How much of the detected material is the compound you want. HPLC usually measures it, stated as a share of total peak area. The figure is relative. It does not confirm identity, which needs a separate test.
What is meant by a triple agonist?
One molecule that binds and switches on three different receptors. Retatrutide is the example that comes up most in current metabolic research. Its three targets are the GLP-1, GIP and glucagon receptors.