Determination of dopexamine hydrochloride in human blood by high-performance liquid chromatography with...

A method is described for the determination of dopexamine hydrochloride at concentrations of 5 to 100 ng/ml in human blood using electrochemical detection. The method uses a Hypersil ODS column and a mobile phase containing heptane sulphonate, orthophosphoric acid, diisopropylamine and disodium EDTA. Blood samples are stabilised immediately after collection by the use of dipotassium EDTA and a high concentration of sodium metabisulphite. The sample preparation procedure consists of a simple de-proteinisation with perchloric acid. The method is accurate, with inter-assay accuracies ranging from 100 to 104%, and is free of interference by blood from different individuals. Known and potential metabolites of dopexamine hydrochloride and a wide range of drugs do not interfere with the method. The method is precise with inter-assay coefficients of variation of 10.6% at 5 ng/ml and of less than 4.2% at higher concentrations. Stabilised blood samples may be stored for over six months at -25 degrees C prior to analysis.