title: Free Base Porphyrins as Ionophores for Heavy Metal Sensors.
abstract: Two functionalized porphyrins: 5,10,15,20-tetrakis(3,4-dimethoxyphenyl) porphyrin (A) and 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin (B) obtained and characterized by us were used as ionophores (I) for preparing PVC-based membrane sensors selective to Ag⁺, Pb2+and Cu2+. The membranes were prepared using three different plasticizers: (bis(2-ethylhexyl)sebacate (DOS), dioctylphtalate (DOP), o-nitrophenyl octyl ether (NPOE) and potassium tetrakis(4-chlorophenyl)borate (KTClPB) as additive. The functional parameters (linear concentration range, slope and selectivity) of the sensors with membrane composition: (I:PVC:KTClPB:Plasticizer) in different ratios were investigated. The best results were obtained for the membranes in the ratio I:PVC:KTClPB:Plasticizer 10:165:5:330. The influence of pH on the sensors response was studied. The sensors were used for a period of four months and their utility has been tested on synthetic and real samples.
authors.affiliation: West University of Timisoara, 4 V. Parvan Ave, Timisoara 300223 Timis, Romania. danavlascici@yahoo.com.
authors.forename: Dana
authors.initials: D
authors.lastname: Vlascici
authors.affiliation: Institute of Chemistry -Timişoara of Romanian Academy, 24 M. Viteazul Ave, 300223-Timisoara, Romania. efagadar@yahoo.com.
authors.forename: Eugenia
authors.initials: E
authors.lastname: Fagadar-Cosma
authors.affiliation: Technical University of Cluj-Napoca, Faculty of Science and Materials Engineering, 15 Constantin Daicoviciu Street, 400020 Cluj-Napoca, Romania. epica@yahoo.com.
authors.forename: Elena Maria
authors.initials: EM
authors.lastname: Pica
authors.affiliation: Technical University of Cluj-Napoca, Faculty of Science and Materials Engineering, 15 Constantin Daicoviciu Street, 400020 Cluj-Napoca, Romania. vioricacosma@yahoo.com.
authors.forename: Viorica
authors.initials: V
authors.lastname: Cosma
authors.affiliation: West University of Timisoara, 4 V. Parvan Ave, Timisoara 300223 Timis, Romania. obizerea@yahoo.com.
authors.forename: Otilia
authors.initials: O
authors.lastname: Bizerea
authors.affiliation: Nationale Institute of Research and Development for Isotopic and Molecular Technologies, 71-103 Donath Street 400293, Cluj-Napoca, Romania. gigim@itim-cj.ro.
authors.forename: Gheorghe
authors.initials: G
authors.lastname: Mihailescu
authors.affiliation: Nationale Institute of Research and Development for Isotopic and Molecular Technologies, 71-103 Donath Street 400293, Cluj-Napoca, Romania. olenic@itim-cj.ro.
authors.forename: Liliana
authors.initials: L
authors.lastname: Olenic
keywords: PVC-matrix.; Porphyrins; heavy metals; ionophores; sensors