Quantification of l-alanyl-l-glutamine in mammalian cell culture broth: Evaluation of different detectors

l-Alanyl-l-glutamine (also known as Ala-Gln or GlutaMAX) is widely used as a stable l-glutamine source in cell culture for the production of biopharmaceuticals. System approaches for the optimization of production processes require the analysis of all major substrates and products. We have compared four alternative detection systems for l-alanyl-l-glutamine in culture broth. Matrix effects prevented the use of ultraviolet or evaporative light scattering detection. Fluorescence detection used in routine amino acid protocols is compatible with culture broth and has a broad linear dynamic range. Mass spectrometry has superior sensitivity and can be integrated into quantitative metabolomic workflows.