Isotopic labelled Riboflavin 5-Phosphate Sodium is the phosphate sodium salt form of riboflavin, a water-soluble and essential micronutrient that is the principal growth-promoting factor in naturally occurring vitamin B complexes.

(-)-Riboflavin 5-phosphate-[13C4,15N2] is the labelled analogue of FMN. FMN is a biological molecule produced by riboflavin kinase from riboflavin (vitamin B2). It has a role as a coenzyme, a bacterial metabolite, a human metabolite, a mouse metabolite and a cofactor.