Luminol/Sulfamic Acid Electrochemiluminescence and Its Application for Dopamine Detection

Herein, sulfamic acid (SA) was utilized, for the first time, to enhance significantly the luminol electrochemiluminescence (ECL). With the SA concentration increased from 0.1 滋mol 窑L^-1 to 500 滋mol 窑L^-1 the ECL intensity increased proportionally. The developed luminol/SA ECL system was employed to detect dopamine (DA) based on its prominent quenching effect. The Stern-Volmer equation of I_o/I= 1+K_sv[DA] could be applied to express well the quenching mechanism of DA in the luminol/SA ECL system. The calibration plot showed that the increase in the DA concentration from 0.5 to 20 滋mol窑L^-1 decreased linearly the ECL intensity with a detection limit of 30 nmol窑L^-1. The luminol/SA ECL system was successfully carried out for DA detection in urine real sample by employing the standard addition method with the excellent recoveries of 103% ~ 105%. Selectivity of the as-developed ECL system was also investigated by using uric acid, ascorbic acid, sugars and amino acids. The results indicated that the ECL intensities changed negligibly in the presence of other substances.