Taguchi OA25 Orthogonal Array Design for the Optimization of La3+-Selective Electrode Prepared by Sol-gel Technique

A sol-gel electrode, based on ethyl 1,2,3,4-tetrahydro-6-methyl-4-phenyl-2-thioxopyrimidine-5-carboxylate (etmptc) as a neutral ionophore, was successfullydeveloped for the detection of la3+ in aqueous solutions. the electrode responds to la3+ion with a sensitivity of 19.7±0.1 mv/ decade over the range 1.0×10?8–1.0×10?1 m and ina ph range of 3.0–10.0. the sol-gel electrode shows detection limit of 3.5×10?9 m. theinfluence of membrane composition, the ph of the test solution, and the interfering ions onthe electrode performance was investigated. the proposed electrode shows gooddiscrimination of la3+ ion from several cations. the effect of temperature on the electroderesponse showed that the temperature higher than 65°c deteriorates the electrodeperformance. the electrode was found to work well under laboratory conditions. thissensor not only was used as an indicator electrode in potentiometric titration of lanthanumion against edta but also was used to determination of la3+ concentration in the presenceof certain interfering ions.