In the present research, a novel and simple disposable solid state potentiometric sensor is proposed and used for determination of codeine in pharmaceutical samples. The sensing membrane which contains codeinium-tetraphenylborate ion pair is coated on strip-shaped pencil leads and also on stainless steel spinal needles. Composition of the coated membrane has been optimized to obtain a Nernstian response. The best performance was observed with the strip-shaped pencil lead as the substrate and the membrane composition of 52.5 mg of PVC, 43.2 mg of o-nitrophenyloctylether (o-NPOE), and 4.3 mg of the ion pair for the sensing membrane.The constructed electrode showed a Nernstian slope of 59.1±0.5 mV decade−1 over the concentration range of 1.0×10−4 to 1.0× 10−1 mol L−1 and a limit of detection of 5.0×10−5 mol L−1 of codeine. The electrode has a response time of 15 s and can be applied in the pH range of 5 to 9. The proposed electrode has been used to measure the codeine contents in pharmaceutical tablets.

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