What is an endotoxin limit, and do research peptides meet it?

An endotoxin limit is the maximum amount of bacterial endotoxin (a fever- and inflammation-causing fragment of Gram-negative bacterial cell walls) a parenteral product is allowed to contain. For injectable drugs, USP chapter <85> and FDA guidance set it with the formula K/M, where K is 5 EU/kg of body weight for intravenous products (EU = endotoxin unit). On a certificate of analysis you'll usually see the result as EU/mg. Detection is done by the LAL (Limulus amebocyte lysate) test. Research peptides are a separate situation. They're sold for laboratory research only, not for human use, so no agency holds them to a legal endotoxin limit. A purity COA (for example one from Janoshik) reports HPLC and mass-spec identity, not endotoxin or sterility, unless that specific test was ordered. Some sellers do post separate LAL results, often against a practical research limit near <1 EU/mg. Bottom line: an endotoxin limit is a defined pharmaceutical standard, and an unbranded research peptide only "meets" it if a lab actually tested that batch and the number is below the limit. Anything injected into a person is a question for a licensed clinician, not a vendor COA.