Automated on-line packed fiber solid phase extraction for determination of urinary catecholamines

Despite the development of an off-line packed fiber solid phase extraction procedure (PFSPE) for urinary catecholamines, automation remains a challenge. Here, we propose an on-line PFSPE-HPLC procedure for automated sample processing and analysis of urinary catecholamines, with good recovery and precision, to avoid manual operation errors. The on-line PFSPE-HPLC procedure has been thoroughly optimized concerning the gradient, valve switch timing, the effects of complexing reagent and buffer solution, and the stability of the nanofibers. Validation of the developed on-line PFSPE-HPLC protocol in urine yielded satisfactory accuracies of 99.6-104.2%, precision below 7.0%, as well as a linear range from 1 ng/mL to 100 ng/mL with a correlation coefficient of 0.999. The developed protocol is herein presented as a potential technology for automated sample pretreatment for the determination of urinary catecholamines.