Metabolomics and IROA
IROA utilizes full metabolic labeling to distinguish between two cell populations, specifically both 5% 13C (to label experimental samples) and 95% 13C (to label control samples). 
How is this achieved?  Compounds are randomly and universally labeled and the relative abundances of the isotopes of carbon are altered; i.e. enriched in one particular isotope and depleted in its other isotopic form. For example,  95% U-13C6-Glucose is not actually 95% 13C6 and 5% 12C6. Instead each carbon atom position (1,2,3,4,5,6) has a 95% chance of being 13C labeled and a 5% chance of being 12C. Compounds such as 5% and 95% U-13C6-Glucose are produced especially for IROA Technologies LLC by Cambridge Isotope Technologies, Inc.
The unique mass spectral patterns of molecules that are 5% 13C and 95% 13C-labeled have the advantage over traditional methods that use no label or use heavy (99%) and light (unlabelled, natural abundance).
The specific signatures in every unique IROA molecule are all mathematically calculable enabling the IROA ClusterFinder™ software tool to easily characterize peaks (as either artifacts, control or experimental compounds), remove artifacts, perform peak correlation analysis to associate adducts with their fragments, calculate carbon number and molecular formula, quantitate the ratio of control to experimental, and normalize each dataset.