Gas liquid chromatography-mass spectrometry (GLC-MS), ion exchange chromatography, high pressure liquid chromatography (HPLC) and other separation procedures are used to isolate and measure the specific activities of the norepinephrine metabolites, 3-methoxy, 4-hydroxyphenylglycol (MHPG) and vanillyl mandelic acid (VMA) in the urine of controls and patients with mental and neurologic disorders.