Biochem/physiol Actions L-Glutamine is an essential amino acid that is a crucial component of culture media that serves as a major energy source for cells in culture. L-Glutamine is very stable as a dry powder and as a frozen solution. In liquid media or stock solutions, however, L-glutamine degrades relatively rapidly. Optimal cell performance usually requires supplementation of the media with L-glutamine prior to use. General description This certified reference material (CRM) is produced and certified in accordance with ISO/IEC 17025 and ISO Guide 34. Other Notes Values of analytes vary lot to lot.