Determination of urinary normetanephrine, metanephrine and 3-methoxytyramine by high-performance liquid chromatography with electrochemical detection: comparison between automated column-switching and manual dual-column sample purification methods.
This report describes a high-performance liquid chromatographic method with electrochemical detection for the simultaneous quantitation of urinary metanephrine, normetanephrine and 3-methoxytyramine. This method, which involves manual dual-column purification steps for the routine determination of urinary metanephrines, is compared with the previously used spectrophotometric Pisano method and an on-line sample preparation procedure, where the automated sequential trace enrichment (ASTED) apparatus is used for the column-switching procedure. In order to automate the metanephrine assay, the enrichment technique was evaluated against the reference chromatographic method. Bio-Rad urine controls gave coefficients of variation of less than 9% at all levels for the reference method. Values of less than 19% were found in the reference range with the enrichment method, and the recovery of 3-methoxytyramine was also too poor to be measured in normal concentrations. The linearity of both methods is sufficient to determine pathological levels of these biogenic amines. Future developments should be focused on decreasing the variation of between-day assays in an on-line, automated procedure.
Volin
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United Laboratories Ltd., Helsinki, Finland.
D000328:Adult; D002648:Child; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004298:Dopamine / Q000031:analogs & derivatives* / Q000302:isolation & purification / Q000652:urine; D004563:Electrochemistry; D006801:Humans; D008676:Metanephrine / Q000302:isolation & purification / Q000652:urine*; D009647:Normetanephrine / Q000302:isolation & purification / Q000652:urine*; D015203:Reproducibility of Results
D009647:Normetanephrine; D008676:Metanephrine; C001746:3-methoxytyramine; D004298:Dopamine