An improved method for the differential assay of 3-O-methylated catecholamines in human urine using ion-pair...

A gas chromatographic method is described for the quantitative determination of urinary normetadrenaline, metadrenaline and 3-methoxytyramine using electron capture detection. The N,O-dipentafluoropropionyl beta-O-ethyl derivatives of normetadrenaline and metadrenaline and the N,O-dipentafluoropropionyl derivative of 3-methoxytyramine were prepared. The amines were purified by ion exchange chromatography and ion pair extraction. Amine derivatives from urine extracts were identified definitively by mass fragmentography. The 24-h excretion value for normetadrenaline in human urine is 167 +/- 95 micrograms (mean +/- S.D.), for metadrenaline is 116 +/- 74 micrograms (mean +/- S.D.) and for 3-methoxytyramine is 82 +/- 68 micrograms (mean +/- S.D.).