Codeine is a derivative of morphine and belongs to the poppy alkaloid group of opiates which can produce euphoria. Codeine is qualified as a drug abuse, while is used as a local anesthetic in many pharmaceutical preparations [1]. Up to now, more sensitive and selective methods for the determination of codeine are still needed to be developed. Electrochemical sensors based on potentiometric detection with ion-selective electrodes (ISEs) are eco-friendly and non-destructive techniques; provide easy construction and manipulation, present good selectivity; have relatively low detection limits; and show a fast response time. This research describes the development of a cheap, user-friendly and highly sensitive solid sate sensor for determination of codeine in various samples. This work is considered a simple PVC based potentiometric ion selective electrode based on the codeinium–tetrapheylborate ion pair as sensing material which is coated on two disposable and cheap substrates i.e. a strip shaped graphite substrate or a steel needle. Effect of several parameters which influence the sensor performance have been investigated and optimized. The graphite based sensor showed a superior behavior over the steel based sensor. The graphite based sensor showed a near nernstian slope of 52.3 mV/decade over the concentration range of 10-3-10-6 mol L-1 of codeine phosphate with the detection limit of 5×10-7 mol L-1. The sensor has been applied to the selective determination of codeine in pharmaceuticals and environmental samples.

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