MIP/GO/GCE Sensor for the Determination of Aminophylline in Pharmaceutical Ingredients and Urine Samples

A new selective molecular imprinted polymer (MIP) was synthesized for electrochemical sensing of aminophylline (AMI). The MIP was fabricated via the co-polymerization of different monomers (acrylamide and methacrylic acid) around the template (AMI) in the presence of a cross-linker (ethylene glycol dimethacrylate) and an initiator (potassium persulfate). The prepared polymers were characterized by CHN elemental analysis, Fourier-transform infrared spectroscopy, atomic force microscopy, and scanning electron microscopy. For electrochemical applications, a voltammetric sensor was constructed by dropping MIP on the glassy carbon electrode surface after modification with the graphene oxide. Electrochemical determinations were achieved using differential pulse voltammetry (DPV), which indicated a wide range (3.7×10-11- 1×10-3 mol L-1) of AMI and a low detection limit (2.1×10-12 mol L-1). Alternatively, MIP was immobilized on a plasticized PVC membrane and deposited as one layer on the GCE to fabricate the potentiometric sensor. In the same context, a potentiometric sensor was constructed and exhibited a linear calibration curve in the concentration range of 2.6×10-9 mol L-1 to 3.1×10-3 mol L-1, with a detection limit of 1.5×10-10 mol L-1. Additionally, the developed methods displayed great selectivity for AMI compared to other competing molecules, high repeatability, and stability. In addition, the proposed methods were successfully applied for AMI detection in pharmaceutical drugs with recovery values (98.2 - 99.6%).