CAS 72-19-5 appears in our catalog under these names: L-Threonine, 98+% , L-Threonine, 98.5+%, Ultrapure, Thermo Scientific , L-Threonine, Cell Culture Reag . Offered by: Thermo Scientific (Alfa Aesar). Available pack sizes: 25g, 100g, 500g, 1kg, 250g.