Potentiometric Determination of Prednisolone in Pharmaceutical Formulations

In this present work, a prednisolone ion selective electrode (PRED-ISE) has been developed. The electrode shows linear response towards prednisolone in the range 3.0×10−6 – 8.6×10−3 M with a detection limit of 2.5×10−6. PRED-ISE was used as an indicator electrode for the potentiometric titration of different concentrations of standard prednisolone against standardized sodium tetraphenyl borate solution and in tablets. The electrode manifests advantages of low resistance, fast response and, most importantly, good selective relativity to a variety of other cations.

Gadolinium(III) Ion-Selective Electrode Based on 3-Methyl-1H-1,2,4-triazole-5-thiol

The 3-methyl-1H-1,2,4-triazole-5-thiol (MTH) was used as a suitable ionophore for fabrication of a new gadolinium(III) ion selective potentiometric sensor. Nitrobenzene (NB) was used as plasticizing solvent mediator and sodium tetraphenyl borate (NaTPB) as an anion excluder. It displays a Nernstian response (19.8± 0.4 mV/decade) in the concentration range of 1.0×10-7to 1.0×10-2M with the detection limit of 7.3×10-8M. The sensor has a very short response time (<10s) and can be used the pH range of 2.9-8.4. electrode was successfully applied as an indicator for gadolinium determination in titration with EDTA.

A polyvinylchloride-based cadmium ion-selective electrode using [Mo2(OAc)2(H2-calix[4]arene)] as an electroactive material

A highly electroactive material Mo2[(OAc)2(H2-calix[4]arene)] is used as a neutral carrier for Cd2 + ions in this paper. The membrane is fabricated by using ionophore [Mo2(OAc)2(H2-calix[4]arene)]:poly(vinyl chloride) (PVC): dibutylphthalate(DBP):sodium tetraphenyl borate (NaTPB) in the ratio of 40:300:470:5 respectively and tetrahydrofuran (THF) used as a solvent. The membrane electrode performed in the concentration range of 9.9 × 10−8–1.0 × 10−1 M (2.34 × 10−5–23.64 mg/mL) having the Nernstian slope of 30.0±1.0 mV and the best detection limit was observed at 9.8 × 10−8 M (2.31 × 10−5 mg/mL). The proposed membrane electrode has the response time of 12 s and a useful working pH range of 1.0–7.0, and used over a period of 10 months and work satisfactorily in the test solution having 30% (v/v) non-aqueous content. Electrode sensor has distinguishable ability for Cd2 + ion with regard to several alkali, alkaline earth, transition and heavy metal ions. It was used in direct potentiometry as an indicator electrode, in the potentiometric titration of 10−3 M Cd2 + solution against 10−2 M of ethylenediaminetetraacetic acid (EDTA).

Membrane Sensors for the Selective Determination of Donepezil Hydrochloride

The construction and electrochemical response characteristics of polyvinylchloride (PVC) membrane sensors for donepezil HCl (DP) are described. The sensing membranes incorporated ion-association complexes of DP cation and sodium tetraphenyl borate (sensor 1), phosphomolybdic acid (sensor 2), or phosphotungstic acid (sensor 3) as electroactive materials. The sensors displayed a fast, stable, and near-Nernstian response over a relatively wide DP concentration range (1 102 to 1 106 M), with cationic slopes of 53.0, 54.0, and 51.0 mV/ concentration decade over a pH range of 4.0 to 8.0. The sensors showed good discrimination of DP from several inorganic and organic compounds. The direct determination of 2.54000.0 g/mL DP showed average recoveries of 99.0, 99.5, and 98.5, and mean RSDs of 1.6, 1.5, and 1.7 at 100.0 g/mL for sensors 1, 2, and 3, respectively. The proposed sensors have been applied for direct determination of DP in two pharmaceutical preparations. The results obtained for determination of DP in tablets using the proposed sensors compared favorably with those obtained using an HPLC method. The sensors have been used as indicator electrodes for potentiometric titration of DP.

Conductometric Studies of Tetraphenyl Arsonium Chloride and Sodium Tetraphenyl Borate in Different Nonaqueous Media

The possibility of ion-pair formation of Ph