USB multiplex analyzer employing screen-printed silver electrodes on paper substrate; A developed design for dissolution testing

Multiplex ion analyzers have been introduced recently for the assay of several inorganic ions, whilst electrochemists have extensively employed screen printed sensors for pharmaceutical analyses. This work aims to develop a USB pluggable sensor with a user-friendly design for multiplex analysis of oppositely charged co-formulated organic ions. The miniaturized screen-printed electrode was developed using silver ink on paper substrate. A compact sensor design was attained by including three electrodes, a single reference electrode along with an indicator electrode for each of the determined ions. Optimized PVC membranes were drop-casted over each of the indicator electrodes for the determination of phenylephrine HCl (PHE) and ibuprofen (IBU). The proposed multiplex potentiometric sensors exhibit Nernstian slopes of 59.2 ± 0.26 and -56.8 ± 0.16 mV/decade for PHE and IBU, respectively, with respective detection limits of 1.6 × 10^-7 and 6.53 × 10^-8 mol L^-1. The fast and stable response of the developed sensor enabled the real-time monitoring of the combined dosage form dissolution. The dissolution profiles obtained by this potentiometric analyzer and an off-line separation technique were compared favourably, albeit our proposed in-line sensor reduced waste and time of analysis. The developed method successfully complies with the most demanding stipulations of green analytical chemistry.