Tetraazacyclohexadeca Macrocyclic Ligand as a Neutral Carrier in a Cr Ion-selective Electrode

Preparation of polyaniline grafted graphene oxide–WO3 nanocomposite and its application as a chromium(iii) chemi-sensor

Polyaniline-grafted-GO@WO₃ was prepared and deposited on a Ag electrode with conducting binders to give a sensor with a fast selective response for Cr³⁺ in the liquid phase. The sensitivity and detection limit are ∼4.4251 mA mM⁻¹ cm⁻² and 0.031 ± 0.010 nM.

Carbon composite-PVC based membrane coated platinum electrode for chromium determination

A new synthesized 1-(2-(1H-imidazole-1-yl)-1-(4-methoxyphenyl)ethylidene)-2-phenyl hydrazine has been used as an ionophore in carbon composite-PVC coated platinum electrode for fabrication of chromium(III)-selective sensor. The homogenization procedure of membrane mixture was performed by applying of the ultrasound in this respect. The sensor shows a good Nernstian slope of 19.62 ± 0.45 mV decade(-1) in a wide linear range concentration of 8.4 × 10(-8)-1.0 × 10(-2)M and a detection limit of 6.8 × 10(-8)M for Cr(NO(3))(3). The proposed electrode has a short response time of about 10s and is reproducible and stable for a period of at least 2 months. The performance of the sensor is pH independent in the pH range of 3.3-5.9 and it also works well in partially non-aqueous medium. The electrode has good selectivity relative to variety of metal ions. The practical analytical utility of the electrode is demonstrated by measurement of Cr(III) quantitatively in multivitamin, mineral water and also as an indicator electrode in the potentiometric titration of chromium (III) against EDTA.

Lanthanide Recognition: an Asymetric Erbium Microsensor Based on a Hydrazone Derivative

N'-(2-hydroxy-1,2-diphenylethylidene)benzohydrazide (HDB) was found tohave a very selective and sensitive behavior towards erbium(III) ions, in comparison tothirteen lanthanide ions, inner transition and representative metal ions and was hence usedas a neutral ion carrier in construction of an Er(III) microelectrode. Theoretical calculationsand conductance studies of HDB to erbium and some other metal ions were carried out andconfirmed selectivity toward Er(III) ions.The best performance was obtained with a membrane contain 3% potassium tetrakis(p-chlorophenyl)borate (KTpClPB) as an anionic additive, 72% dibutyl phthalate (DBP) assolvent mediator, 5% HDB, and 20% poly(vinyl chloride) (PVC). The proposed Er(III)microelectrode exhibits a near Nernstian response of 17.5±0.5 mV per decade of erbiumactivity, and a very wide linear range 1.0×10-3-3.0×10-10 M. It can work well in the pHrange of 3.0-9.0. The lower detection limit (LDL) of the microelectrode was calculated tobe 2.0×10-10 M.

Schiff bases as cadmium(II) selective ionophores in polymeric membrane electrodes

The construction and performance characteristics of polymeric membrane electrodes based on two neutral ionophores, N,N'-[bis(pyridin-2-yl)formylidene]butane-1,4-diamine (S1) and N-(2-pyridinylmethylene)-1,2-benzenediamine (S2) for quantification of cadmium ions, are described. The influences of membrane compositions on the potentiometric response of the electrodes have been found to substantially improve the performance characteristics. The best performance was obtained with the electrode having a membrane composition (w/w) of (S1) (2.15%):PVC (32.2%):o-NPOE (64.5%):KTpClPB (1.07%). The proposed electrode exhibits Nernstian response in the concentration range of 7.9x10(-8) to 1.0x10(-1) M Cd2+ with limit of detection 5.0x10(-8) M, performs satisfactorily over wide pH range (2.0-8.0) with a fast response time (10 s). The sensor has been found to work satisfactorily in partially non-aqueous media up to 30% (v/v) content of methanol, ethanol and acetonitrile and could be used for a period of 2 months. The analytical usefulness of the proposed electrode has been evaluated by its application in the determination of cadmium in real samples. The practical utility of the membrane electrode has also been observed in the presence of surfactants.

A cerium(III) selective polyvinyl chloride membrane sensor based on a Schiff base complex of N,N'-bis[2-(salicylideneamino)ethyl]ethane-1,2-diamine

A polyvinyl chloride (PVC) based membrane sensor for cerium ions was prepared by employing N,N'-bis[2-(salicylideneamino)ethyl]ethane-1,2-diamine as an ionophore, oleic acid (OA) as anion excluder and o-nitrophenyloctyl ether (o-NPOE) as plasticizer. The plasticized membrane sensor exhibits a Nernstian response for Ce(III) ions over a wide concentration range (1.41 x 10(-7) to 1.0 x10 (-2) M) with a limit of detection as low as 8.91 x 10(-8) M. It has a fast response time (<10s) and can be used for 4 months. The sensor revealed a very good selectivity with respect to common alkali, alkaline earth and heavy metal ions. The response of the proposed sensor is independent of pH between 3.0 and 8.0. It was used as an indicator electrode in potentiometric titration of fluoride, carbonate and oxalate anions and determination of cerium in simulated mixtures.