In this work, a simple, cheap, sensitive, and selective modified carbon paste electrode is proposed for the electroanalytical determination of Levofloxacin (LEVO), the drug used to treat pneumonia caused by coronavirus. The electrochemical polymerization method was applied to create a thin poly-murexide film (POMUR) on the bare carbon paste electrode (BCPE) surface to enhance its electrocatalytic activity. The peak current response of LEVO obtained by POMUR/CPE was increased by 14.2 μA compared to BCPE. Scanning electron microscopy (SEM) and cyclic voltammetry (CV) techniques were employed to characterize BCPE and POMUR/CPE. Under the optimal experimental circumstances, the prepared sensor was capable of determining LEVO with a low limit of detection (LOD) of 7.18 nM (S/N = 3) for a linear dynamic range of 25 -1 × 10 3 nM utilizing differential pulse voltammetry (DPV). Moreover, the practical applicability of POMUR/CPE for determining LEVO in pharmaceutical formulations and biological samples (human serum) demonstrated high sensitivity and selectivity with a recovery of 95.08 -100.5 %.

Since the fluoroquinolone family of antibiotic drugs has recently been widely utilized to treat pneumonia during the COVID-19 pandemic spread, we shed light on them in our work. In the current investigation, a poly-murexide modified carbon paste electrode (PMUX/CPE) was utilized to detect second-generation fluoroquinolone antibiotic ciprofloxacin (CFLOX) in human serum samples and pharmaceutical formulations. PMUX/CPE showed high accuracy, good sensitivity, and selectivity toward CFLOX. For the morphological analysis of the fabricated sensor, scanning electron microscopy (SEM) was used. PMUX/CPE had an outstanding ability to enhance electron transfer compared to the unmodified electrode. The obtained differential pulse voltammograms (DPVs) exhibited that under ideal experimental conditions, the oxidation peak currents of CFLOX were linearly proportional to their concentration in the range of 0.05 to 3.00 µM, with a detection limit (LOD) and quantification limit (LOQ) of 0.0057 µM, and 0.0190 µM, respectively. With a recovery of 93.25%-104%, this method was effectively applied to detect CFLOX concentrations in pharmaceutical tablets and spiked human serum.