Electrochemical Analysis of Pharmaceuticals

All chemicals used were of analytical grade and used as received without any further purification. All solutions were prepared with deionised water of resistivity not less than 18.2 MΩ cm from a Milli-Q Integral 3 system from Millipore UK (Watford, UK). Hexaamineruthenium (III) chloride (RuHex, 98%), castor oil, potassium ferricyanide (99%), potassium ferrocyanide (98.5–102%), sodium hydroxide (>98%), potassium chloride (99.0–100.5%), acetaminophen (≥99.0%), and phosphate-buffered saline (PBS) tablets were purchased from Merck (Gillingham, UK). (R)-Phenylephrine hydrochloride was purchased from TCI Chemicals (Zwijndrecht, Belgium). Carbon black (Super P®, >99+%) was purchased from Fisher Scientific (Loughborough, UK). Multi-walled carbon nanotubes (MWCNT, 10–30 μm length, 10–20 nm outer diameter) were purchased from Cheap Tubes (VT, USA). Recycled poly(lactic acid) (rPLA) was purchased from Gianeco (Turin, Italy). Commercial conductive PLA/carbon black filament (1.75 mm, ProtoPasta, Vancouver, Canada) was purchased from Farnell (Leeds, UK). Recycled non-conductive PLA filament was produced in-house, as shown previously [28 (link)]. Real samples of pharmaceuticals Max Strength Cold & Flu Capsules (Optipharma), Max Strength Cold & Flue Relief powder (Sainsbury’s), and Cold & Flu Powder (Beechams) were obtained from local convenience stores.