we report the determination of catecholamines ( dopamine , norepinephrine , and epinephrine ) and their 3-o-methylated metabolites ( 3-methoxytyramine , normetanephrine , and metanephrine ) in urine by gas chromatography/mass spectrometry , with use of stable isotopically labeled internal standards .
C0014563
epinephrine
C0025562
metanephrine