Determination of trace amounts of dopamine by flow-injection analysis coupled with luminol-Ag(III) complex chemiluminescence detection

A novel flow injection analysis-direct chemiluminescence (FI-CL) method has been developed for determination of trace amounts of dopamine (DA) based on the enhancing effect of DA on the CL reaction of luminol with an Ag(III) complex in alkaline solution. Under optimum conditions, CL intensities are proportional to the concentration of DA in the range of 1.0 x 10(-10) to 4.0 x 10(-8) mol L-1. The detection limit is 3.0 x 10(-11) mol L-1 for DA (3s), with a relative standard deviation (n = 13) of 2.3% for 1.0 x 10(-8) mol L-1 DA. This method has also been applied for the determination of DA in commercial pharmaceutical injection samples. On the basis of the CL spectra and the results of the free-radical trapping experiment of this work, a reaction mechanism for this CL reaction is proposed and discussed. Copyright (c) 2010 John Wiley & Sons, Ltd.