The concentrations of glutamine and ammonia in commercially available cell culture media

The amino acid glutamine is an essential nutrient for cells in culture. In aqueous solutions such as liquid culture media, glutamine spontaneously decomposes into ammonia. In this study, we examined the toxicity of ammonia for two different cell lines. In mouse hybridoma cell cultures, viable cell counts were reduced at exogenous ammonia concentrations of 1000 microM. In the human promyelocytic cell line however, viable cell counts were shown to be reduced at exogenous ammonia concentrations of 300 microM. Next, we determined ammonia and glutamine levels in 11 commercially available media on the day of delivery. It was found that all media contained significantly less glutamine than prescribed. Ammonia was found in all media with concentrations ranging up to 1000 microM. Storage at both 4 degrees C and 20 degrees C caused a further degradation of glutamine and significant accumulation of ammonia in all media. The degradation curves of the various media were used to calculate the first order degradation constant k, which can be used to determine the kinetics of the spontaneous decomposition in culture media. These results suggest that precautions must be taken to avoid the deterioration of commercially available culture media, because of the decay of glutamine. Long storage times lead to a rapid decay of glutamine and an accumulation of the toxic degradation product ammonia.