Lead(II)-Selective Electrode Based on Phenyl Disulfide

Fast Potentiometric Analysis of Lead in Aqueous Medium under Competitive Conditions Using an Acridono-Crown Ether Neutral Ionophore

Lead is a particularly toxic heavy metal that is present above acceptable levels in the water of many countries. This article describes a quick detection method of lead(II) ions using a polyvinyl chloride (PVC)-based ion-selective membrane electrode containing an acridono-crown ether ionophore by potentiometry. The electrochemical cell exhibits a Nernstian response for lead(II) ions between the concentration range of 10^−4 to 10^−2 M, and can be used in the pH range of 4⁻7. The applicability of this sensor was verified by measuring a multicomponent aqueous sample. Under the given conditions, this electrode is suitable for the selective quantitative analysis of lead(II) ions in the presence of many additional metal ions.

Carbon nanotube composite coated platinum electrode for detection of Ga(III)

This study demonstrates the application of composite multi-walled carbon nanotube (MWCNT) polyvinylchloride (MWNT-PVC) based on 7-(2-hydroxy-5-methoxybenzyl)-5,6,7,8,9,10-hexahydro-2H benzo [b][1,4,7,10,13] dioxa triaza cyclopentadecine-3,11(4H,12H)-dione ionophore for gallium sensor. The sensor shows a good Nernstian slope of 19.68 ± 0.40 mV/decade in a wide linear range concentration of 7.9 × 10(-7) to 3.2 × 10(-2)M of Ga(NO(3))(3). The detection limit of this electrode is 5.2 × 10(-7)M of Ga(NO(3))(3). This proposed sensor is applicable in a pH range of 2.7-5.0. It has a short response time of about 10s and has a good selectivity over nineteen various metal ions. The practical analytical utility of this electrode is demonstrated by measurement of Ga(III) in river water.

A highly selective and sensitive disposable carbon composite PVC-based membrane for determination of lead ion in environmental samples

A Pt wire coated with phenyl hydrazone derivative-carbon composite in a poly(vinyl chloride) membrane was used for detection of lead. The sensor had a Nernstian slope of 29.46+/-0.41 mV/decade over a wide linear concentration range of 7.7 x 10(-7) to 1.0 x 10(-1) mol L(-1) for Pb(NO(3))(2). The detection limit was 3.2 x 10(-7) mol L(-1) and the electrode was applicable in the pH range of 3.7-6.3. It had a short response time of approximately 6s and was used at least for 70 days. The electrode has exhibited good selectivity for Pb(II) relative to 19 other metal ions. The functionality of the proposed sensor was also investigated in binary water-alcohol mixture and it concluded that 23% water-methanol and 20% water-ethanol content could not bring out any changes in its potential. The practical analytical utility of the electrode was demonstrated by measurement of Pb(II) in mineral rock and potentiometric titration of sulfate anion.

Platinum electrode coated with a bentonite–carbon composite as an environmental sensor for detection of lead

A Pt wire coated with a bentonite-carbon composite in a poly(vinyl chloride) membrane was used for detection of lead. The sensor has a Nernstian slope of 29.42+/-0.50 mV per decade over a wide range of concentration, 1.0 x 10(-7) to 1.0 x 10(-3) mol L(-1) Pb(NO(3))(2). The detection limit is 5.0 x 10(-8) mol L(-1) Pb(NO(3))(2) and the electrode is applicable in the pH range 3.0-6.7. It has a response time of approximately 10 s and can be used at least for three months. The electrode has good selectivity relative to nineteen other metal ions. The practical analytical utility of the electrode is demonstrated by measurement of Pb(II) in industrial waste and river water samples.

Construction and characterization of potentiometric sensor for the determination of oxytetracycline hydrochloride

The construction and performance of plastic membrane (PME) oxytetracycline hydrochloride (OTC)-selective electrodes, based on three types of ion-pairs, OTC-tetraphenylborate (TPB), OTC-phosphotungstate (PT) and OTC-silicotungstate (SiT), as the electroactive substance in a plasticized PVC membrane with dibutylphthalate (DBP), were described. Furthermore, internal solid contact sensors (ISCS) OTC-selective sensors, based on a conducting polypyrrole (PPy) film immobilized on a platinum or glassy carbon electrode surface casted by a plasticized PVC membrane were constructed and evaluated. A novel optimization methodology in a numerical expression, comprehensive quality index (CQI) for a sensor, was used to optimize the composition of the membrane in the preparation of PME and screen the parameter of electropolymerization in the preparation of ISCS. Several PMEs and ISCSs were fully characterized and evaluated. An ISCS (Pt/PPy/PVC (OTC-TPB)) showed an excellent Nernstian response over the linear concentration range of 4.0 x 10(-7)-5.0 x 10(-2) M with the slope of 60.6 mV per decade (at 25 degrees C). The limit of detection was 1.0 x 10(-7) M of OTC (0.03 ppm). The response time was <25 s. The sensor was successfully used for the analysis of OTC in pharmaceutical formulation by using direct potentiometry.

Potentiometric Performance of Silver Ion-Selective Electrodes Based on Tridentate Schiff Base Derivatives

To examine the directivity for improving the silver ion discrimination ability of a Schiff base, three kinds of tridentate ligands were synthesized and compared with the similar quadridentate ligand as the silver ionophore. Among the Schiff base derivatives tested, 3-(2-pyridylethylimino)-2-butanoneoxime, having one oxime and a pyridine substituent, was found to be the best ionophore for a silver-ion electrode. The electrode based on this derivative exhibited good silver-ion selectivity, -log Kpot(Ag+,K+) = 3.8, comparable to that of a quadridentate Schiff base, N,N'-bis(2'-hydroxyimino-1'-phenylpropyleden)-1,3-propanediamine, reported previously, except for a pseudo Nernstian response (35.6 mV decade(-1)) with a wide silver-ion activity change in the activity change from 5.0 x 10(-7) to 7.9 x 10(-2) mol dm(-3).