Ion Transfer Behavior of Protonated Phenazopyridine at the Liquid/Liquid Interface Modified by Functionalized Hybrid Mesoporous Silica Membrane

The transfer behavior of a clinical drug, phenazopyridine hydrochloride, at the water/1 ,6-dichlorhexane(W/DCH) interface modified by functionalized mesoporous silica membrane was studied by cyclic voltammetry and differential pulse voltammetry. It was found that the phenazopyridine (PAP) can be protonated to form phenazopyridine cation (HPAP(+)) under acidic condition, which can transfer at such a membrane-modified W/DCH interface. According to the relationship between the transfer peak current and the scan rate, as well as the equation of Randles-Sevcik , the diffusion coefficient of HPAP(+) in the functionalized hybrid mesoporous silica membrane was calculated to be 5. 14 x 10(-8) cm(2)/s. In addition, the electrochemical response of ion-transfer of HPAP(+) at the W/DCH interface modified by functionalized hybrid mesoporous silica membrane is much higher than bare PET membrane , which can improve the electrochemical detection performance of phenazopyridine cation. Moreover, the ionic partition diagram of HPAP(+) at the W/DCH interface modified by functionalized hybrid mesoporous silica membrane was obtained by differential pulse voltammetry , which can not only understand the distribution of HPAP(+) under different conditions (pH value and interfacial potential) , but also obtain the distribution coefficient and ion-transfer Gibbs free energy of HPAP(+), which helps to understand the transmembrane process of HPAP(+) across biological membrane and provide a new electrochemical method to detect phenazopyridine hydrochloride.