A Nanopipette Supported Oil/Water Interface Sensor for the Kinetics Analysis and Determination of Phenothiazine Derivatives

Phenothiazine is an intermediate in the synthesis of drugs, and its derivatives, i.e., chlorpromazine (CPZ) and promethazine (PMZ), are both the major tranquilizers. Herein, a nanoscale soft sensor constructed utilizing the interface between two immiscible electrolyte solutions (ITIES) for CPZ and PMZ drugs was introduced. A nanopipette with a 60 nm diameter orifice was used to support the ITIES, and voltammetry and amperometry were used for the qualitative and quantitative determination of these two drugs crossing the liquid/liquid (L/L) interface. Half-wave potentials (Δwoφ1/2) of 0.107 V and 0.092 V (vs. Δwoφ1/2,TEA+) for PMZ+ and CPZ+ transfer from water to 1,2-dichloroethane (DCE) were obtained, respectively. Subsequently, the kinetics and effective hydrophilicity of these two drugs were thoroughly investigated. Moreover, there were two calibration curves for the determination results between the current and the concentration range for CPZ+ and PMZ+ by cyclic voltammetry (the concentrations range from 0.1 to 10 mmol−1) and amperometry (the concentrations range from 0.02 to 10 mmol−1). Finally, the actual drug recovery for these two drugs ranged from 94.83% to 111.02%, which indicates the accuracy in actual medicine is good. The above work provides a soft nano-liquid/liquid interfacial sensor with applications in drugs, including kinetics studies and drug determination, and many applications in detecting pharmaceutical molecules, cellular secretion and other bioorganic compounds.