A novel polymeric membrane sensor for determining titanium (III) in real samples: Experimental, molecular and regression modeling

The construction of a potentiometric titanium(III)-selective electrode based on methyliresorcinarene (CMCR) incorporated into a poly(vinyl chloride) (PVC) matrix is reported. The polymeric membrane incorporates 8.0 mg CMCR as an electroactive sensing material, 59.0 mg dioctylphthalate (DOP) as a plasticizer, 3.0 mg sodium tetraphenyl borate (NaTPB) as an anionic additive and 30 mg PVC as a neutral matrix exhibiting a Nernstain potential response of 30.38 +/- 0.15 mV per decade in the concentration range from 1 x 10(-6) to 1 x 10(-2) M with a detection limit of 8.9 x 10(-7) M and fast response time of 15s. The proposed sensor was successfully applied to determine titanium cations in real samples and the obtained results were compared to those of spectroscopy methods such as AAS and ICP instruments. The structure of CMCR ligand and its complexation with some common cations were investigated using quantum mechanical DFT calculations where the titanium (III) cation showed prominent affinity for the CMCR carrier. The regression model was applied to obtain the membrane composition model of Ti(III)-ISE affecting the potential response of the polymeric sensor. The results show that the regression model can be used as a practical method for obtaining the Nernstian slope of the proposed sensor in this study. (C) 2015 Elsevier B.V. All rights reserved.