The Core is able to develop analytical methods for specific endogenous metabolites of interest and to quantitate levels in various matrices depending upon client needs. We currently have assays developed for a number of specific analytes, including arginine, select nucleobases, nucleotides and nucleosides, glutamine, branched chain amino acids, branched chain keto-acids, tryptophan, kynurenine, serotonin, cinnabarinic acid, 3-hydroxyanthranillic acid, kynurenic acid, melatonin, xanthurenic acid, and indole. The best quantitation is achieved if a stable isotope version of your metabolite of interest is available but related isotopically labeled compounds can be utilized as an internal standard with careful control of matrix conditions utilized for preparation of standard curves (see Thakare, et al, 2016, Quantitative analysis of endogenous compounds. Journal of Pharmaceutical and Biomedical Analysis 128:426-437). Please contact the Core director to discuss your specific needs.