SPE-HPLC determination of catecholamines using an affinity principle.

Solid-phase extraction (SPE) with the affinity chromatography principle was applied for high performance liquid chromatography (HPLC) determination of catecholamines in patients urine samples. Electrochemical amperometric detection (ED) was used for all HPLC analyses and both analytical and microbore columns were tested for optimal chromatographic resolution of all analyzed catecholamines. Capacity ratio k' and detection limits were evaluated for all columns used. Precolumn affinity chromatographic procedure of catecholamines with diphenylboronic acid (DPBA) in alkaline medium improved their retention on different commercial SPE reversed-phase cartridges. After clean-up and preconcentration step the complex catecholamine-diphenylboronic acid was degraded by acidic pH and eluted from SPE cartridge. After SPE affinity step catecholamines were analyzed by HPLC-ED. The optimal elution solutions was chosen also as suitable SPE cartridges. Extraction recoveries of catecholamines were 89.6-93.3% with relative standard deviation RSD = 3.8-4.3%. Total analysis time was 30 min including 15 min for the preseparation procedure.