Glossary
Every term, in plain words
A result nobody can read is not published in any meaningful sense. Every technical word that appears anywhere on the record is here.
- Identity
- The first question, and a gate: a vial can be 99% pure and still be the wrong molecule entirely. Nothing else is worth measuring until this passes.
- Content / potency
- A 5 mg vial at 75% net peptide content holds 3.75 mg. Every dose drawn off that label is short by a quarter.
- Purity
- Peptides are built one amino acid at a time, and some chains stop early or pick up damage. Those fragments are what an impurity peak is.
- Sterility & endotoxin
- Endotoxin is shed by dead bacteria and survives sterile filtration. Injected, it causes fever, chills and a drop in blood pressure.
- Heavy metals
- Left over from the metal catalysts used in synthesis. Measured in parts per million against pharmaceutical limits.
- Residual solvents
- Acetonitrile and methanol are used to purify peptides and are meant to be driven off afterwards. What stays behind is measured here.
- LC-MS
- Liquid chromatography–mass spectrometry. Separates the sample, then weighs each part precisely enough to tell one peptide from another.
- RP-HPLC
- Reversed-phase high-performance liquid chromatography. Each component leaves the column at its own time, drawing the peaks on the chromatogram.
- ICP-MS
- Inductively coupled plasma mass spectrometry. Burns the sample in plasma and weighs what is left, which is how lead at 0.1 ppm is measurable.
- GC
- Gas chromatography. The sample is heated until any residual solvent evaporates, then each solvent is separated and measured.
- LAL
- Limulus amoebocyte lysate. A clotting reaction that responds to endotoxin at tiny concentrations.
- Amino acid analysis
- Breaks the peptide back into its amino acids and counts them, which gives real milligrams rather than a percentage of the powder.
- Bioburden
- Measured by growing whatever is in the sample on a plate and counting the colonies — the CFU figure.
- EU/mg
- Endotoxin units per milligram — the endotoxin measure.
- CFU/mg
- Colony-forming units per milligram — the live-bacteria measure.
- ppm
- Parts per million. 1 ppm is one milligram in a kilogram.
- Retention time
- Each substance travels through the column at its own speed, so retention time is how a peak gets identified.
- Area %
- The area under a peak is proportional to how much of that substance is present, so a 4% peak is roughly 4% of the material.
- Truncation
- Synthesis adds one amino acid at a time. When a step fails, the chain stops short — a truncated peptide that is not the drug and can provoke an immune response.
- Oxidation product
- Some amino acids react with oxygen, usually from poor handling or storage. The result is a slightly heavier molecule that no longer works the same way.
- Assay
- A single test that answers one question about the sample — what it is, how much of it there is, what else is in it. Five of them decide a score.
- Aliquot
- A measured portion split off from the sample so each test gets identical material — and so a sealed portion is left over if a result is disputed and has to be re-run.