Effect of pretreating samples with boric acid before liquid- chromatographic determination of urinary catecholamines

• Published in: Clinical chemistry (Baltimore, Md.) Vol. 33; no. 1; pp. 108 - 112
• Main Authors: Degel, F, Zuman, P, Jandik, P, Gilch, G
• Format: Journal Article
• Language: English
• Published: England Am Assoc Clin Chem 01.01.1987
• Subjects: Boric Acids; Catecholamines - urine; Chromatography, High Pressure Liquid; Chromatography, Ion Exchange; Electrochemistry; Humans; Hydrogen-Ion Concentration; Solutions
• ISSN: 0009-9147; 1530-8561
• DOI: 10.1093/clinchem/33.1.108

Isolation of catecholamines on prepacked gravity-fed ion-exchange columns in conjunction with liquid-chromatographic separation is occasionally subject to disturbances of unknown origin, especially after injection of H3BO3 eluates from the ion-exchange columns onto the chromatography column. Peak spreading, sometimes even peak splitting, has been observed in many laboratories--effects easily confused with those sometimes caused by voided columns or by impurities. To elucidate the origins of these interferences, we performed a combined voltammetric and chromatographic investigation. We show that complexation of the catechol group by borate ions and dissociation of those pH-labile complexes in the course of the chromatographic separation is the cause of those peak distortions. Addition of a small volume of diluted HCI to the borate eluates eliminates such interference and leads to reproducible, easily interpretable chromatographic separations.