Analytical Sciences

A Highly Selective Potentiometric Sensor of Molybdate Based on a μ-Oxo-bridged Manganeseporphyrin Dimer

Zheng-Hui FANG,*^,** Zhi-Xiang HAN,* Xiao-Bing ZHANG,* Guo-Li SHEN,* and Ru-Qin YU*

*State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry & Chemical Engineering, Hunan University, Changsha, 410082, P. R. China
**Yueyang Vocational & Technical College, Yueyang, 414000, P. R. China

A novel high-selective potentiometric sensor for molybdate was prepared with a PVC membrane combining μ-oxo-bis[5,10,15,20-tetra(p-methylphenyl)porphinatomanganese(III)] [[Mn(p-Me)TPP]₂O] as an electroactive material and 2-nitrophenyl octyl ether (o-NPOE) as a plasticizer in the percentage ratio of 3:65:32, [Mn(p-Me)TPP]₂O:o-NPOE:PVC (w:w). The sensor exhibited a linear response with a Nernstian slope of 30.5 mV per decade within a concentration range of 2.1 × 10^-6 to 1.0 × 10^-1 M MoO₄^2-, with a working pH range from 5.0 to 12.5, and a fast response time of less than 15 s. The electrode showed improved selectivity toward molybdate with respect to common coexisting anions compared to monometalloporphyrin counterparts. Several electroactive materials and solvent mediators were compared and the experimental conditions were optimized. The sensor is preliminary applied to the assay of MoO₄^2- in corrosion inhibitor samples with satisfactory results.

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