High-performance liquid chromatographic analysis of catecholamines in biological samples by liquid/liquid extraction...

A prepurification procedure for the determination of catecholamines in biological samples was studied to simplify the procedure and increase selectivity and recovery. The procedure is based on liquid/liquid extraction of catecholamine-borate complexes. Under optimal conditions, catecholamines formed complexes with diphenylborate in an alkaline NH4Cl/NH4OH buffer that were extracted with n-heptanol. Catecholamines were reextracted into an HCl-acidified solution, followed by reversed-phase ion-pair high-performance liquid chromatographic separation with fluorometric detection. Application of the method to various samples of rat tissues and human urine showed procedural simplicity, high selectivity, and high recovery (about 90% or more for tissue samples). This method can be used for pharmacological studies on catecholamines.