In this research, construction and performance characteristics of a PVC membrane electrode based on dicylohexyl-18-crown-6 (DCH18C6) as a neutral ionophore have been described. The influence of the membrane composition on the potentiometric response of the electrode has been investigated and optimized to improve the performance characteristics. The best performance was obtained with the membrane composition (w/w %) of DCH18C6 (7%): PVC (60%): DOP (23%): C (10%). The proposed electrode exhibits a Nernstian slope of 19.78 mv /decade within the wide concentration range of 1×10-2 to 1×10-6 M. The limit of detection for Y3+ ion was found to be 7.33×10-7 M and the potentiometric response was independent from the pH of the test solution in the pH range of 2.0 - 5.0. Also, it has a response time of 20 s for yttrium (III) concentrations ranging from 1×10-2 to 1×10-6 M. The sensor could be used for a period of 45 days. The analytical usefulness of the proposed electrode has been evaluated by its application in the determination of fluoride ion in mouthwash and toothpaste real samples.

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