Improved sample preparation in determination of urinary metanephrines by liquid chromatography with electrochemical detection.
In this relatively simple procedure for extracting metanephrines from urine, after an internal standard (4-hydroxy-3-methoxybenzylamine in 1 mmol/L HCl) is added, the sample is hydrolyzed in a boiling water bath, then treated with ammonia and alumina. Excess ammonia is removed under reduced pressure and the sample is applied to a 1-mL Bond Elut SCX column, which is washed, and metanephrines and internal standard are eluted with 0.5 mmol/L sodium acetate/acetonitrile (3/1 by vol). Of this elute, 5 microL is injected into a 15 cm x 4.6 mm (i.d.) column packed with 5-microns octadecylsilyl silica particles, which is eluted with a mobile phase containing tetramethylammonium perchlorate. Peaks are detected coulometrically at +0.28 V. In the resulting chromatogram, metanephrines give sharp peaks, well resolved from peaks for solvent and internal standard. There are no extraneous peaks for catechols or mono-oxygenated phenylethylamines. Results correlated well (r = 0.999, n = 13) with those by earlier described liquid-chromatography.
Gupta
R N
RN
Department of Laboratory Medicine, St. Joseph's Hospital, Hamilton, Ontario, Canada.
D000537:Aluminum Oxide; D000641:Ammonia; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D004837:Epinephrine / Q000031:analogs & derivatives*; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008676:Metanephrine / Q000652:urine*; D009647:Normetanephrine / Q000652:urine; D011786:Quality Control
D009647:Normetanephrine; D008676:Metanephrine; D000641:Ammonia; D000537:Aluminum Oxide; D004837:Epinephrine