NOVEL polyvinyl chloride (PVC) potentiometric sensors are constructed for determination of variamine blue (VB). Different
methods for electrode fabrication including; modification with the VB-TPB ion pair, modification with sodium tetraphenylborate or soaking of the plain electrode in the ion-pair suspension, have been described. Electrode matrix compositions were optimized on the basis of effects of type and content of the modifier as well as influence of the plasticizers. The fabricated electrodes worked satisfactorily in the concentration range from 10 -6 to 10-2 M of VB. Electrodes modified with VB-TPB showed the best performance (Nernstian slope 62.0±0.7 mV decade-1) with fast response time of about 8 sec and adequate lifetime (4 weeks). The developed electrodes have been successfully applied as end point indicator electrode for the potentiometric titration of 6.75-20.25 mg VB with high accuracy and precision. The solubility products of different VB ion-pair were determined conductometrically.
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