Flow-injection determination of trace amounts of dopamine by chemiluminescence detection

A flow-injection analysis (FIA) for the determination of dopamine has been developed. The method is based on the inhibition effect of dopamine on the iron(II)-induced chemiluminescence (CL) of 10,10'-dimethyl-9,9'-biacridinium dinitrate (lucigenin). The presence of a non-ionic surfactant, polyoxyethylene (23) lauryl ether (Brij 35), caused an increase in the inhibition effect. The present method allows the determination of dopamine over the range 1 x 10(-8)-2 x 10(-7) mol dm(-3). The relative standard deviation was 0.7% for eight determinations of 6 x 10(-8) mol dm(-3) dopamine. The detection limit (S/N = 3) was 2 x 10(-9) mol dm(-3) with the sampling rate of 40 samples h(-1) The effect of ether catecholamines and compounds of similar structure on the lucigenin CL reaction was studied: quinone, hydroquinone, norepinephrine. pyrocatechol and L-dopa suppressed the CL intensity. (C) 1999 Elsevier Science B.V. All rights reserved.