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

• The fabrication of a novel titanium(III)-ISE based on CMCR in a PVC matrix.
• The application and validation of the proposed sensor in real samples.
• The regression model applied for the membrane composition to get the Nernstian slope.
• The Gaussian 09 applied for CMCR and its complexation with some cations.
• The sensor has a low detection limit, fast response and wide concentration range.

The construction of a potentiometric titanium(III)-selective electrode based on methylcalix[4]resorcinarene (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 × 10−6 to 1 × 10−2 M with a detection limit of 8.9 × 10−7 M and fast response time of 15 s. 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.