Potentiometric behaviour of ion selective electrodes based on iron porphyrins: the influence of porphyrin substituents on the response properties and analytical determination of diclofenac in pharmaceutical formulations.

The potentiometric response characteristics of diclofenac selective electrodes based on Fe(III) tetraphenylporphyrin-chloride (Fe(III)TPP-Cl) and Fe(III) tetrakis(pentafluorophenyl)porphyrin-chloride (Fe(III)TPFPP-Cl) in different mediator solvents and ionic additives are compared. The sensitivity, working range, detection limit, response mechanism, and selectivity of the membrane sensor show a significant dependence on the type of carrier substituent and on the pH value of the sample solution. Studies performed with different amounts of cationic additive (tetra-n-octylammoniumbromide (TOABr)) and anionic additive (sodium tetraphenylborate (NaTPB)) in the membranes allowed the determination of the potentiometric mechanism of action of the used metalloporphyrins.

Construction and evaluation of PVC and sol-gel sensor membranes based on Mn(III)TPP-Cl. Application to valproate determination in pharmaceutical preparations.

The construction and general performance of new valproate-selective electrodes based on manganese(III) tetraphenylporphyrin [Mn(III)TPP-Cl], as an ionophore, are presented. The ionophore was incorporated into PVC and ceramic membranes (sol-gel) based on methyltriethoxysilane. The influence of membrane composition and pH and the effect of lipophilic cationic and anionic additives in PVC membranes were investigated concerning their influence on the slope, response time, selectivity and lifetime of the electrodes.

Ion selective electrodes for penicillin-G based on Mn(III)TPP-Cl and their application in pharmaceutical formulations control by sequential injection analysis.

The work describes the construction, evaluation and analytical application of ion selective electrodes sensitive to penicillin-G antibiotics for pharmaceutical products analysis. Different types of polymeric membranes based on PVC (poly(vinyl chloride)) and EVA (ethyl-vinyl-acetate), without internal reference solution, were prepared using 5,10,15,20-tetraphenylporphyrinate (TPP) manganese(III) (Mn(III)TPP-Cl) as electroactive material. Different additives such as tetra-n-octylammoniumbromide (cationic additive) and sodium tetraphenylborate (anionic additive) were incorporated into the membranes to evaluate their influence on electrodes performance.

Ion-selective electrodes based on metalloporphyrins for gibberellic acid determination in agricultural products.

This work describes the construction, evaluation and analytical application of electrodes selective to the gibberellate anion for the determination of gibberellic acid in agricultural products. Several types of PVC membrane electrodes without internal reference solution were prepared using the manganese(III) complex of meso-tetraphenylporphyrin (TPP) as ionophore and dibutyl phthalate (DBP), as plasticizer. The incorporation of lipophilic chemical species as additives, was also carried out aiming the evaluation of the response characteristics of the electrodes.