PVC-based Mn(III) porphyrin membrane-coated graphite electrode for determination of histidine

Abstract

The construction, performance characteristics, and application of a polymeric membrane coated on a graphite electrode with unique selectivity toward histidine are reported. The electrode was prepared by incorporating chloro (5, 10, 15, 20-tetraphenylporphyrinato) manganese-(III) [Mn(TPP)Cl] into a plasticized poly(vinyl chloride) membrane. The influences of membrane composition, pH, and foreign ions were investigated. Calibration plots with near Nernstian slopes for histidine were observed, -55.4 mV/decade, over a linear range of four decades of concentration (1 x 10-5 to 1 x 10-1 M). The electrode has a detection limit of 5 x 10-6 M histidine and shows high a fast response time of about 1 min. The electrode shows high selectivities high toward histidine over several amino acids and common inorganic anions.