Peptide research glossary
Every term that turns up on a certificate or a product page, defined in one sentence or two. Alphabetical.
What is an aliquot?
A measured portion divided out from a larger sample. Splitting reconstituted material into single-use aliquots means each portion is frozen and thawed exactly once, avoiding the cumulative damage that repeated freeze-thaw cycles inflict on a whole batch.
What is bacteriostatic water?
Sterile water containing roughly 0.9% benzyl alcohol, a preservative that inhibits bacterial growth. The preservative is what allows a vial to be entered repeatedly without organisms multiplying in it.
Full guide: Bacteriostatic Water vs Sterile Water for Peptides →
What does cold chain mean?
An unbroken sequence of temperature-controlled storage and transport from producer to end user. Each break adds cumulative heat exposure, and because the damage accumulates rather than resets, the total time out of range is what matters.
What is an endotoxin?
A fragment of bacterial cell wall that survives sterilisation. Endotoxins can interfere with biological assays even when no living organism remains, which is why endotoxin testing is reported separately from sterility.
Full guide: Endotoxin & Sterility Testing in Research Peptides →
What is HPLC?
High-performance liquid chromatography — a technique that separates the components of a mixture by pushing it through a packed column under pressure. Relative peak areas give the purity figure quoted on a certificate.
Full guide: What Does 99% Peptide Purity Mean? HPLC & Mass Spec Explained →
What is mass spectrometry?
A technique that ionises a sample and measures the mass-to-charge ratio of the ions produced. For peptides it answers the identity question: does the measured mass match the mass calculated from the intended sequence?
Full guide: What Does 99% Peptide Purity Mean? HPLC & Mass Spec Explained →
What is lyophilisation?
Freeze-drying. Water is removed from a frozen sample by sublimation under vacuum, leaving a dry porous solid that is far more stable than the same material in solution.
What is purity, on a peptide label?
The proportion of detected material that is the target compound, usually measured by HPLC and expressed as a percentage of peak area. It is a relative measure and says nothing about identity, which is confirmed separately.
Full guide: What Does 99% Peptide Purity Mean? HPLC & Mass Spec Explained →
What is quality control testing?
The checks run on a batch before release — identity, purity, appearance, and where relevant sterility and endotoxin — recorded against a lot number so a specific vial traces back to specific data.
What is a triple agonist?
A single molecule that binds and activates three different receptors. Retatrutide is the example most cited in current metabolic literature, acting at the GLP-1, GIP and glucagon receptors.