Preparation and analytical application of the novel Hg(II)-selective membrane electrodes based on oxime compounds

Novel Hg(II)-selective poly(vinyl) chloride (PVC) membrane electrodes based on oxime compounds of (4-(4-methylphenylaminoisonitrosoacetyl)biphenyl, I1; 4-(4-clorophenylaminoisonitrosoacetyl)biphenyl, I2; N,N-bis[1-(4-phenylphenyl)-2-hydroxyimino-2-(4-chloroaniline)-1-ethylidene]-diethylenetriamine, I3 and N,N-bis[1-(4-phenylphenyl)-2-hydroxyimino-2-(4-chloroaniline)-1-ethylidene]- 1,3-propanediamine), I4 were developed. Effects of the species and ratios of ionophore, plasticizer, PVC and lipophilic additive on the potentiometric response of electrodes were investigated in order to determine the electrode specifications. Overall results revealed that the optimum membrane composition was: 4% ionophore, 64% plasticizer (o-NPOE), 31% PVC, and 1% lipophilic additive (NaTPB). Obtained results showed that the electrodes have detection limit of 1.76 × 10−6, 1.68 × 10−6, 2.35 × 10−6 and 2.44 × 10−6 and have linear responses of 34.2, 33.4, 35.9 and 37.6 mV/pHg2+ for a wide concentration range of Hg(II) ions. According to durability studies, the electrodes can be used for approximately 1 month without any considerable divergence in potential values. Analytical applications of the electrodes were performed and it was found that developed electrodes can successfully be used as indicator electrodes for the potentiometric titration of Hg(II) ion with EDTA solution.

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