An in-vitro assay begins with a purchase order, not a pipette. Before a plate is booked, a bench slot reserved or a diluent volume calculated, someone in the laboratory has to read the vial label and understand precisely what it authorises — and what it does not. On UK-supplied research peptides, the phrase carrying the most weight is only four words long: Research Use Only. Its meaning is narrower than many newcomers assume, and settling that meaning early prevents wasted material, failed runs and uncomfortable compliance conversations further down the line. What ‘Research Use Only’ Actually Means on a UK Peptide Vial On a UK peptide label, Research Use Only…