Biochemical pathways form a very complex network of reactions within biological material. At Metabolomic Discoveries we have to tackle this maze every day in order to deliver high quality results to our customers. We offer a ‘navigation system’; an advanced modeling approach using isotope labeled substances (e.g. 13C-glucose). In fact, we are chasing the labeled isotopes through the whole metabolic network. In combination with our concentration measurements of intracellular metabolites, the new approach enables us to answer important questions like: Which metabolic pathways are being used under different conditions? Can I improve my production pathway? Are there any bottlenecks hampering product synthesis? How much of the carbon introduced flows into by-products?