Fig. 4.

Representative total ion chromatography for patient urine organic acid analysis (gas chromatography/mass spectroscopy) from Subject A (panel A) and Subject B (panel B). Relative abundance is on the vertical axis while time is on the horizontal axis. Selected peaks are indicated for (1) lactic acid, (2) 3-hydroxybutaric acid, (3) succinic acid, (4) fumaric acid, (5) malic acid, and (6) the internal standard (undecanedioic acid). Malic acid eluted at 19.32 min and 19.79 min for Subject A and Subject B, respectively. This is further illustrated in the overlay of specific ions (m/z).