Chromatograms of serum samples with and without IS
Serum samples with or without IS were injected into the GP-HPLC system, followed by reaction with TC (A) and TG (B) reagents. Comparison of chromatograms between serum alone (black, dotted line) and serum with quinone pigment from ADPS (red, solid line) as IS. The chromatograms are representative of three separate experiments.