New approach to the simultaneous analysis of catecholamines and tyrosines in biological fluids

New high-performance liquid chromatographic (HPLC) methods with amperometric–CoulArray detection were developed for simultaneous analyses of norepinephrine, epinephrine, l-DOPA, dopamine, 3-nitrotyrosine, m-, o-, and p-tyrosines. Overall, detection limit was in the low pmol range with amperometry, and in the low fmol range for the CoulArray method. Linear (r2=0.99) detector performances were observed in the ranges of 2–200 pmol with amperometry, and 0.2–20 pmol for the CoulArray method. Analytical precision values were better than 80 and 95% for HPLC–amperometry and HPLC–CoulArray method, respectively. These methods offer sensitivity, specificity, minimal sample requirement, and especially the HPLC–CoulArray method allows simultaneous assessment of various similar biomolecules.