Determination of Trihexyphenidyl hydrochloride drug in tablets and urine using a potentiometric carbon paste electrode

[Display omitted] •A new carbon paste electrode for determination of a Trihexyphenidyl ion (THP) drug was designed.•THP is used to treat symptoms of Parkinson's disease. Abuse of (THPCl) can be fatal for overdose intoxication.•This electrode gives a slope of 57.8±0.4mV over 1.2×10−6–1.0×10−2M with a limit of detection of 7.1×10−7M.•Electrode showed accurate and reproducible detection of THP ion in urine and tablets samples. A carbon-paste electrode for Trihexyphenidyl hydrochloride drug (THPCl) was prepared and fully characterized in terms of composition, usable pH range and temperature. The electrode was applied to the potentiometric determination of (THP) ion in its pharmaceutical preparation and urine samples. The sensor is based on Trihexyphenidyl–tetraphenylborate as ion-pair (THP-TPB) dissolved in dibutyl phthalate as pasting liquid. The modified electrode showed a near-Nernstian slope of 57.8±0.4mV/decade over the concentration range of 1.2×10−6–1.0×10−2M with a limit of detection of 7.1×10−7M. The electrode has a short and stable response time of 5 s. and it can be used in a pH range of 2.5–4.8. It is clearly selective for THP ion over tested cations and excipients commonly added to drug formulations. Drug is determined successfully in tablets and urine using this modified carbon paste electrode as an indicator electrode.