Selective and simultaneous electrochemical detection of amoxicillin and paracetamol in pharmaceuticals and serum using a mixed-ligand poly(Co(II)-phenanthroline, diresorcinate) modified electrode

Abstract

Transition metal coordination compounds are emerging as good alternative electrode modifiers for detection of various electroactive analytes due to their several appropriate features such as that they can provide high sensitivity, selectivity, electrical conductivity, and a larger surface area. This study reports the use of carefully designed and prepared cobalt(II) complex using resorcinolate (HR⁻) and 1,10-phenanthroline(phen) having a formula of Co(HR)₂(phen) (DHRPCo), with electroactivity and a tetrahedral geometry. The later properties are important for its easy polymerization and impart porous surface on the electrode surface. This complex was used for the fabrication of metal complex-based polymer film-modified electrode for the simultaneous analysis of amoxicillin (AMX) and paracetamol (PTM). Using cyclic voltammetric and electrochemical impedance spectroscopy methods, the potentiodynamic (employing a potential range) synthesis of poly(diresorcinate-1,10-phenanthrolinecobalt(II)) modified glassy carbon electrode (poly(DHRPCo)/GCE) was confirmed. The poly(DHRPCo)/GCE in an equimolar combination of AMX and PTM showed adequately separated oxidative peaks with significantly improved peak current, indicating the polymer film's electrocatalytic property towards the oxidation of AMX and PTM, as compared to the unmodified GCE. The poly(DHRPCo)/GCE electrode demonstrated a linear oxidative peak current response to AMX and PTM concentrations ranging from 0.01 to 400.0 μM under optimum pH and square wave voltammetric configurations. The detection limits were 20.50 nM for AMX and 4.03 nM for PTM. While interference recovery errors were less than 4.84 % for both analytes, the range of spike recovery rates for AMX and PTM was 99.00 % to 100.45 % and 99.33 % to 100.05 %, respectively. The technique showed outstanding electrode stability and a high degree of agreement between the detected and nominal values of AMX and PTM in tablet samples. These results confirm the reliability of the developed approach for simultaneous quantification of AMX and PTM in diverse real-world samples. Its application to pharmaceutical tablets and human blood serum further highlights its potential as an effective analytical tool.