Effect of carbon in-line filters on catecholamine analysis by high-performance liquid chromatography with coulometric...

Biogenic amines were analysed by high-performance liquid chromatography with electrochemical detection according to the method of Kilpatrick et al. [J. Neurochem., 46 (1986) 1865]. Equal amounts of structurally related catechols, i.e. noradrenaline (NA), dopamine (DA), dihydroxybenzylamine (DHBA) and dihydroxyphenylacetic acid (DOPAC), produced electrochemical signals of unequal sizes. Removal of the carbon in-line filter preceding the analytical electrochemical cell markedly increased the peak areas for NA, DA and DOPAC. For DA, this filter effect was larger at pH 4.80 and gradually diminished at lower pH (4.60, 4.42, 4.20). These results indicate that the efficiency of electrochemical detection of catechols can be compromised by the use of carbon in-line filters.