the method is based on the preliminary isolation of monoamines ( dopamine , norepinephrine , epinephrine , and serotonin ) , their precursor amino acids ( tyrosine , 3,4-dihydroxyphenylalanine , tryptophan and 5-hydroxytryptophan ) , and their major metabolites ( 3-methoxytyramine , normetanephrine , 3,4-dihydroxyphenylacetic acid , homovanillic acid , vanillylmandelic acid , 3-methoxy-4-hydroxyphenylethyleneglycol , and 5-hydroxyindoleacetic acid ) by chromatography on small columns of amberlite cg-50 and dowex 50w , and by ethyl acetate extraction .
C0028351
norepinephrine
C0014563
epinephrine