Determination of Cobalt(II) by a New PVC Membrane Coated Graphite Electrode Based on 6-chloro-11- azabenzo[a]phenothiazin-5-one as a neutral ion carrier

Document Type: Research Paper


1 Young Researchers and Elite Club, Yadegar-e-Imam Khomeini (RAH) Shahr-e-Rey Branch, Islamic Azad University, Tehran, Iran

2 Department of Chemistry, Yadegar-e-Imam Khomeini (RAH) Shahre-rey Branch, Islamic Azad University, Tehran, Iran


Cobalt has great biological effects on human beings and also other living organisms, hence its determination is very important. In this regard, a novel coated graphite electrode was designed for determination of Co2+ ions by exploiting 6-chloro-11- azabenzo[a]phenothiazin-5-one as a neutral ion carrier, for the first time. The foremost function was witnessed from the membrane composition of PVC (29%), Potassium tetrakis (4-chlorophenyl) borate (2%) as an ionic additive,6-chloro-11-azabenzo[a]phenothiazin-5-one (9%) as ionophore and Dioctylphthalate (60%) as Plasticizer. The linearity domain of the membrane sensor was from 5×10-7 to 1×10-2 Mol L-1 with the Nernstian slope value of 30.1 mV.Decade-1. The potential response of the designed electrode was also investigated in non-aqueous mediums and it was found out that the electrode is also able to be used in systems that are entailed of 20% of ethanol and acetone organic solvents. The response time and lifespan of the electrode was 5 S and 3 months respectively. The sensor selectivity was also evaluated by match potential method over other cations and it shows an eminent selectivity towards Co2+ over all of the inspected ions. The applicability of the electrode in the potentiometric titration with EDTA was also investigated. In the end, the proposed electrode was utilized for determination of Co2+ in four aqueous specimens as real samples.