Functionalized graphene oxide-based electrode material for the potentiometric detection of codeine phosphate in commercial cough syrups for forensic applications.

The current trend in the detection of forensic or banned drugs has attracted many researchers to the development of engineered nanoparticle-based sensor devices for the rapid detection of these drugs at affordable costs. Herein, we report the development of functionalized graphene oxide active nanosheets (GO-Bpb) for the detection of codeine phosphate in commercially available cough syrup using potentiometric and colorimetric methods. The active material was characterized for the successful intercalation by spectroscopic and microscopic techniques. The sensor strip was fabricated by spin-coating the active material onto Whatman filter paper, incorporating copper electrodes on both sides, with a Teflon separator. Upon dipping into the various concentrations of the test solutions, the variation in the voltage was measured due to the analyte interactions on the active material until the lowest possible concentration. For the colorimetric method, the stock solution of GO-Bpb vs. various concentrations of codeine was measured by UV-Vis spectroscopy for the quantification of the analyte at a lower concentration. It resulted in a limit of detection (LoD) of 0.0412 mg/mL. The cost-effective, reproducible strip-based detection paves the way to achieve a more sensitive and selective method with a LoD of 0.0018 mg/mL for the on-site detection of illicit drugs during crime scene investigation.