Nanomolar Simultaneous Determination of Amlodipine and Uric acid at the Novel Carbon Paste Electrode Modified with Magnetic Carbon Nanotubes/Diatomite Earth Composite

In this work, we use synthesized magnetic carbon nanotubes/diatomite earth composite (CNTs/DE) to fabricate the novel modified carbon paste electrode (CNTs/DE/CPE). The modified electrode was developed and used as a sensitive electrochemical sensor for simultaneous determination of amlodipine (AML) and uric acid (UA). Cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry (CA) methods were used for the measurements. The presence of the CNTs/DE in the electrode composite leads to rapid acceleration in electron transfer reaction of AML and UA at CNTs/DE/CPE. Under optimized conditions and using DPV method, the modified sensor provides a linear response versus UA and AML concentrations in the range of 0.02-250 and 0.04-140 mu M and with a detection limit of 0.011 mu M and 0.021 mu M (S/N=3), respectively. The fabricated sensor offered numerous advantages such as excellent sensitivity, good stability and high selectivity toward UA and AML determination. The modified electrode was used for determination of UA and AML in human urine and serum with satisfactory results.