L-Glutamine 200 mM Solution (29.23 mg/mL). L-Glutamine is an essential amino acid required by virtually all mammalian and insect cells grown in culture. L-Glutamine is also more labile in cell culture solutions than other amino acids. The rate and extent of L-glutamine degradation are related to storage temperatures, age of the product, and pH. All cell culture media are formulated to contain appropriate amounts of L-glutamine to support cell growth well beyond the expiration date of the media. However, if L-glutamine is suspected to be a limiting factor during cell culture, a simple test of ‘spiking’ the medium with a small amount of L-glutamine will determine whether or not more is required. Simply add a small amount of L-glutamine (~ 2 mM final concentration) to the culture medium. If the cell growth rate increases, L-glutamine is most likely deficient and more should be added. It has applications for cell culture, cell growth, and viability.