Novel Drug Selective Sensors for Simultaneous Potentiometric Determination of both Ciprofloxacin and Metronidazole in Pure form and Pharmaceutical Formulations

To investigate the ability of incorporating more than one ion pair in the same selective electrode's membrane, and so constructing an electrode sensitive to either Ciprofloxacin (CFX) or Metronidazole (MZL) according to the standard filling solution of the electrode, subsequently determine the two drugs CFX and MZL Simultaneously in their combined solutions, 3 PVC membrane drug selective sensors were constructed for CFX and MZL analysis intended. The electro active materials were CFX-Phosphotungstic Acid (CFX-PTA), MZL-Phosphotungstic Acid (MZL-PTA) and a composition of CFX-PTA+MZL-PTA. The characterization and analytical properties were determined, and the casting selective membranes of the selective electrodes were plasticized by di-n-butyl phthalate (DBP). Each of the assembled electrodes have internal reference Ag/AgCl electrode. Also, the gathered sensors have external reference Ag/AgCl electrode. The developed sensors showed near Nernstian response for ion pair percentages of 6%, and 7% for CFX-PTA, MZL-PTA, respectively. The electrodes demonstrated a rapid responses of 10-16 sec for a period of 13-15 days, with no changes that have meaningful results in the electrodes parameters. The suggested sensors have a measurement pH ranges 2.0-6.0 for CFX, and 2.0-5.0 for MZL without using any buffer. The sensors were used as indicator electrodes for direct determination of CFX and MZL in pharmaceutical preparations with mean relative standard deviation less than 2% that indicating good precision, as well as in pure form solutions with average recovery of 99.96%, 99.93% and 99.83% (CFX) or 99.88% (MZL) and a mean relative standard deviation of 0.05%, 0.18% and 0.06% (CFX) or 0.18% (MZL)% at 1 mM (367.8 μg/mL CFX, or 171.2 μg/mL MZL) for CFX-PTA, MZL-PTA, and CFX-PTA+MZL-PTA sensors respectively.