coa peptide FAQ

Multiple peaks mean impurities, but the question is what kind. If the secondary peaks appear at retention times very close to the primary peak (within 1–2 minutes), they're likely structurally related. Deletion sequences (n−1 or n−2 peptides missing one or two amino acids), diastereomers (wrong stereochemistry at one position), or incomplete side-chain deprotection. These impurities can interfere with biological assays because they may bind the same receptor or enzyme with different affinity. If the secondary peaks are distant (>5 minutes difference), they're probably unrelated contaminants from synthesis reagents or column bleed. Request the supplier identify all peaks >2%. Legitimate suppliers can tell you exactly what they are.

Do not use this peptide in vivo or in immune cell cultures. Endotoxin levels above 1.0 EU/mg can activate Toll-like receptor 4 (TLR4) signaling pathways, triggering cytokine release that will confound any immune-related assay or metabolic study. For in vitro work with non-immune cell lines, it may be acceptable if endotoxin response isn't a study variable. But it's still a signal of poor purification quality. Request a replacement batch or filter the reconstituted solution through a 0.22 micron filter to remove endotoxins before use.

'Negative' without a quantitative EU/mg measurement is insufficient for biological research. Contact the supplier and request the actual LAL assay result in EU/mg. If they can't provide a number, the batch wasn't tested properly. Assume endotoxin levels are unknown and either send a sample for independent testing or reject the batch. For in vivo metabolic studies using survodutide, undocumented endotoxin contamination is the most common cause of unexplained inflammation and inconsistent results.