Performances of a multidimensional on-line SPE-LC-ECD method for the determination of three major catecholamines in native human urine: validation, risk and uncertainty assessments.

A novel, multidimensional on-line SPE-LC method with electrochemical detection is described for the fully automated and direct analysis of the catecholamines norepinephrine, epinephrine and dopamine in urine. The integrated extractive clean-up of the raw biofluid is based on a SPE-column packed with restricted access material (RAM) which is modified with the affinity ligand nitrophenylboronic acid. The method was fully validated according to a recent approach based on an accuracy profile. The acceptance limits were set at +/-15% of the nominal concentration values. The method was found accurate over a concentration range from 15 to 500 microg/l for norepinephrine, from 5 to 500 microg/l for epinephrine and from 50 to 500 microg/l for dopamine. The relative risk for the use of the validated method in routine analysis was also assessed based on this validation strategy. It was found that at most 3.5% of future sample measurements will fall outside the acceptance limits. This demonstrates the high reliability of the analytical method described. Moreover, the measurements uncertainties were deduced from the validation experiments without any additional effort.