The Determination of Urinary Metanephrine and Normetanephrine by High Performance Liquid Chromatography with Ultraviolet Absorbance Detection

Abstract

43 B m , CSFR ABSTRACTThe sensitive and specific direct analysis of urinary normetanephrine and metanephrine (both free and conjugated) was achieved utilizing reversed-phase high performance liquid chromatography and W detection. The urine specimens were hydrolysed in a boiling water bath and treated with isoamyl alcoho1:toluene to eliminate interference from urinary pigments or related chemical compounds. The methoxyamines were isolated by the passage through a small ion-exchange column and then pre-concentrated by a rapid set of solvent (ethyl acetate:acetone) extractions before being injected into the chromatographic column.Detection was achieved with W absorbance detector at 280 nm and metanephrines were quantified by standard addition method. For both metanephrine and normetanephrine the standard curve was linear over the range of 15-300 pmol/L and practical lower detection limits were about 100 nmol/L for actual urine samples, which are not too different from those using electrochemical detector. Samples can be injected at 10-min intervals.The values for a patient with pheochromocytoma and for other patients are given.