Selective kinetic method based on detecting the intermediate product in successive reactions

A selective kinetic method based on detecting the intermediate product in successive reactions was developed. The method relies on the peak-shaped kinetic curve resulting from the reaction and detection mode. The underlying principle of this method is choosing two proper measurement times where the interference species produces equal signal intensities while the analyte to be determined produces different signal intensities. So with the mixture, the difference in signals at these same two times yields a value related to the concentration of the analyte. This allows selective determination of one analyte in binary mixtures or simultaneous determination of both. The proposed method was applied to the selective determination of epinephrine in four catecholamine mixtures based on their successive reactions with dissolved oxygen in alkaline solution.