Article révisé par les pairs
Résumé : A method is described for the extraction of NH4 + from biological samples. This method can be combined with the enzymatic conversion of NH4 + to glutamate, which can then be used for measuring 15N isotopic enrichment. Emphasis is laid on the difficulties encountered when the samples contain NH4 + together with the amide derivative of monoaminodicarboxylic acids. Copyright © 1982 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim