Herein, a novel electrochemical sensor for simultaneous analysis of esomeprazole (EZM) and diclofenac sodium
(DICLS) in binary mixture was developed. This proposed sensor is carbon paste electrode (CPE) modified with
reduced graphene oxide (rGO) and Co(OH)2 nano-flakes (CHNF). This sensor was designed to tailor the extraordinary
properties of rGO and CHNF to produce synergistic electro-catalysis with significantly improved electroanalytical
response compared to an unmodified bare CPE. Several techniques were used to characterize the
new developed electrochemical sensor. The electrochemical performance was improved by optimizing the effects
of pH, scan rate, amounts of rGO/CHNF, frequency and other parameters. The new sensor was successfully
applied for determination of the cited mixture, where the linearity was achieved in the range of 2.5–155
×10−8Mand 1.5–105 × 10−8Mwith detection limits of 8 × 10−9Mand 5×10−9Mfor DICLS and EZM, respectively.
The fabricated sensor was used for determination of the mixture in pharmaceutical preparations, human
serum and urine.