Figure 2: Detection of arginine metabolites by LC/MS: Extracted ion chromatograms of ADMA (A), D7 ADMA(B), SDMA (C), D6 SDMA (D), NMMA (E), arginine (F), 13C6- arginine (G), citrulline (H) and 13C5 citrulline (I) are shown. Hydrophilic interaction chromatography (HILIC) of authentic compounds and their internal standards was performed using Phenomenex HILIC column with solvent 10mM ammonium acetate and 100% acetonitrile with 0.1% formic acid. The column was equilibrated with 95% solvent B and 5% solvent A initially. The gradient was: 95-15% solvent B over 8 min, 15% solvent B for 6 min, 15-95% solvent B for 1 min and then finally 95% solvent B for 10 min. The eluent was subjected electrospray ionization mass spectrometry (ESI/MS) and the analytes were detected in the multiple reaction monitoring mode (MRM). X axis is denotes time of elution during chromatographic run and the Y axis represents the ion intensity of the extracted ion chromatogram of the daughter ion following ESI of the analyte in the MRM mode. The MRM transitions that are followed for the individual analyte are depicted with each parent molecular ion to daughter fragment that was monitored.