L-Glutamine is an essential amino acid that is a crucial component of culture media and serves as a major energy source for cells in culture. L-Glutamine is very stable as a dry powder and as a frozen solution. However, in liquid media or stock solutions, L-Glutamine degrades relatively rapidly. Toxic degradation products of L-glutamine (ammonium ions) can interfere and may cause damage to cells. Optimal cell performance usually requires supplementation of the media with L-Glutamine just before use. This solution is prepared in cell culture grade water.