Abstract: The present invention relates to a method for preparation of labeled metabolic products, comprising the steps (a) providing a biological sample in vitro, (b) contacting the biological sample with a labeling buffer comprising a labeled substrate, wherein the substrate comprises at least one carbon atom and represents an educt or intermediate of a metabolic process of the biological sample and wherein the label is a stable isotope, (c) washing the biological sample using a wash-buffer, wherein said wash-buffer comprises a carbon resource such that the biological sample is precluded from carbon deficiency during said washing, wherein said carbon resource comprises the substrate according to step b), wherein said substrate in the wash-buffer may be labeled or unlabeled, (d) quenching the biological sample such that metabolic processes within the biological sample are slowed down or stopped and (e) extracting the labeled metabolic product from the biological sample.

Abstract: The present invention relates to a method for preparation of labeled metabolic products, comprising the steps (a) providing a biological sample in vitro, (b) contacting the biological sample with a labeling buffer comprising a labeled substrate, wherein the substrate comprises at least one carbon atom and represents an educt or intermediate of a metabolic process of the biological sample and wherein the label is a stable isotope, (c) washing the biological sample using a wash-buffer, wherein said wash-buffer comprises a carbon resource such that the biological sample is precluded from carbon deficiency during said washing, wherein said carbon resource comprises the substrate according to step b), wherein said substrate in the wash-buffer may be labeled or unlabeled, (d) quenching the biological sample such that metabolic processes within the biological sample are slowed down or stopped and (e) extracting the labeled metabolic product from the biological sample.