Abstract: An IROA Matrix of metabolite compounds is disclosed. Each of whose compounds has a molecular weight of 2000 AMU or less, and is present as first and second isotopomers that are equally present at two predetermined isotopomeric balances, and contain 2 to 10% of a first isotope, and 90 to 98% of a second isotope, respectively. A reagent pair for transforming a natural abundance mass spectral analysis metabolite sample into an IROA sample is also disclosed and comprises two reactively identical reagents that constitute first and second isotopomers containing 2 to 10% of a first isotope, and 90 to 98% of a second isotope, respectively. Each of the reagent pair contains the same reactive group that reacts with and bonds to a functional group of one or more compounds present in a composition of biologically-produced metabolite compounds. Methods of making and using the above and related materials are also disclosed.