RAPID AND SENSITIVE ASSAY OF DOBUTAMINE IN PLASMA BY HIGH-PERFORMANCELIQUID-CHROMATOGRAPHY AND ELECTROCHEMICAL DETECTION

A sensitive and specific high-performance liquid chromatographic metho d with electrochemical detection was developed for measuring dobutamin e in human plasma samples. Following an external standard method, 0.1 ml of EDTA-glutathione plasma was diluted on ice with 0.2 ml of a 5% t richloracetic acid solution. The mixture was centrifuged, filtered, an d 30 mul were injected. Assessment was done by electrochemical detecti on. The assay was linear from 1 to 400 ng/ml plasma. For determination of dobutamine we also used a liquid-liquid extraction method routinel y applied for plasma catecholamines. Liquid-liquid extraction requires application of 100-1000 mul of plasma. The standard curve was linear from 0.1 to 600 ng/ml. Absolute recovery of dobutamine was 90 +/- 3% w ith the liquid-liquid extraction procedure and 91 +/- 3% with the prot ein precipitation method. For both methods dobutamine was separated on Nova-Pak C18 columns. The mobile phase used was 0. 1 molar phosphate buffer-acetonitrile (80:20, v/v) with 1-octanesulfonic acid and trieth ylamine as ion-pair reagents. The pH was adjusted to 2.7.