AX-R08 — Endotoxin above index specification

Endotoxin is measured on a minority of the material in this index — roughly a quarter of batches carry a figure — and it is the measurement whose absence is least defensible, because it is the one that cannot be inferred from anything else. A 99.4 %-pure peptide can carry a gram-negative endotoxin burden that no chromatogram will show.

The index's specification of 5.0 EU/mg is a screening threshold, not a safety limit, and the distinction is important. A genuine limit is dose-dependent: the pharmacopoeial threshold for parenteral administration is 5.0 EU per kilogram of body weight per hour, which converted to a per-milligram limit depends entirely on how much is administered. The endotoxin dose-limit calculator on this site does that arithmetic; the specification here does not attempt to.

Where this rule fires the index reports the measured value, the method (kinetic chromogenic, gel-clot or turbidimetric), the laboratory, and the specification applied. It draws no conclusion about suitability for any use, because these are research compounds and the index's position on administration is stated on the disclaimer.

Flagged batches cluster on water quality at the fill step rather than on synthesis, which is what the chemistry predicts: endotoxin arrives with water and is untouched by anything that happens on a resin. A high-purity lot carrying a measurable burden is a coherent and ordinary result, and depyrogenated water at fill removes it.