Paper-based potentiometric sensing devices modified with chemically reduced graphene oxide (CRGO) for trace level determination of pholcodine (opiate derivative drug).

Robust, reliable and cost-effective paper-based analytical device for potentiometric pholcodine (opiate derivative drug) ion sensing has been prepared and characterized. A printed pholcodinium (PHL) ²⁺ /5-nitrobarbiturate (NB) ^- ion-association complex as a sensory material-based all-solid-state ion-selective electrode (ISE) on a chemically reduced graphene oxide (CRGO) solid-contact, and a printed all-solid-state Ag/AgCl reference electrode, has been combined on a hydrophobic paper substrate coated with fluorinated alkyl silane (CF ₃ (CF ₂ ) ₇ CH ₂ CH ₂ SiCl ₃ , C ^F ₁₀ ). The sensors revealed a potentiometric slope of 28.7 ± 0.3 mV dec ^-1 ( R ² = 0.9998) over a linear range starting from 2.0 × 10 ^-7 M to 1.0 × 10 ^-2 M and a detection limit of 0.04 μg mL ^-1 . The repeatability and stability of the pholcodine paper-based sensor was found to be 2.32%. The RSD% ( n = 6) was found to be 2.67% when using five different paper-based sensors. The sensor revealed an excellent selectivity towards PHL over dextromethorphan, codeine, ephedrine, carbinoxamine, caffeine, ketamine, and K ⁺ , Na ⁺ and Ca ²⁺ ions. It showed a good recovery (94-104%) for the determination of PHL in different artificial serum samples. The presented paper-based analytical device was successfully introduced for PHL determination in different pharmaceutical formulations ( i.e. syrups and suspensions) containing pholcodine. The current work can be considered as a promising possible analytical tool to obtain cost-effective and disposable paper-based potentiometric sensing devices. These devices can be potentially manufacturable at large scales in pharmaceutical, clinical and forensic applications for opiate drug assessment.
Competing Interests: The authors declare that there are no conflicts of interest. All authors have approved the manuscript and agree with the submission to your esteemed journal.
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