Barkha Gupta

Strontium(II)-selective electrode based on a macrocyclic tetraamide.

A new PVC membrane electrode based on 5,7,12,14-dibenzo-2,3,9,10-tetraoxa-1,4,8,11-tetraazacyclotetradecane (I) as an ion carrier, o-nitrophenyloctyl ether (o-NPOE) as solvent mediator and sodium tetraphenylborate (NaTPB) as lipophilic additive was fabricated and investigated as Sr(2+)-selective electrode. The best performance was exhibited by the membrane having composition 8:200:4:120 (I:o-NPOE:NaTPB:PVC). The electrode exhibited a Nernstian response for strontium ion over a wide concentration range 3.98 x 10(-6) to 1.0 x 10(-1)M with a slope of 29.0+/-0.1 mV/decade of concentration and a detection limit of 2.82 x 10(-6)M. It showed a response time of less than 10s and could be used for at least 3 months without any divergence in potential. The proposed electrode showed a good discriminating ability towards strontium(II) ion over a wide variety of other metal ions including alkali, alkaline earth, transition, and heavy metal ions. The electrode can be used in the pH range of 2.5-10.5 and in mixtures containing up to 35% (v/v) non-aqueous content. It was used as an indicator electrode in potentiometric titration of strontium ion against EDTA.

Potentiometric Sensors Enabling Fast Screening of the Benign Prostatic Hyperplasia Drug Alfuzosin in Pharmaceuticals, Urine and Serum

The construction and characterization of potentiometric membrane electrodes are described for the quantification of alfuzosin, a drug used in a mono- and combined therapy of benign prostatic hyperplasia (BPH). The membranes of these electrodes consist of alfuzosin hydrochloride-tetraphenyl borate, (Az-TPB), chlorophenyl borate (Az-ClPB), and phosphotungstate (Az(3)-PT) ion associations as molecular recognition reagent dispersed in PVC matrix with dioctylpthalate as plasticizer. The performance characteristics of these electrodes, which were evaluated according to IUPAC recommendations, revealed a fast, stable and liner response for alfuzosin over the concentration ranges of 8.3 x 10(-6) to 1.0 x 10(-2) M, 3.8 x 10(-6) to 1.0 x 10(-2) M, 7.5 x 10(-7) to 1.0 x 10(-2) M AzCl with cationic slopes of 57.0, 56.0 and 58.5 mV/decade, respectively. The solubility product of the ion-pair and the formation constant of the precipitation reaction leading to the ion-pair formation were determined conductometrically. The electrodes, fully characterized in terms of composition, life span and usable pH range, were applied to the potentiometric determination of alfuzosin hydrochloride ion in different pharmaceutical preparations and biological fluids without any interference from excipients or diluents commonly used in drug formulations. The potentiometric method was also used in the determination of alfuzosin hydrochloride in pharmaceutical preparations in four batches with different expiration dates. Validation of the method showed suitability of the proposed electrodes for use in the quality control assessment of alfuzosin hydrochloride. This potentiometric method offers the advantages of high-throughput determination, simplicity, accuracy, automation feasibility, and applicability to turbid and colored sample solutions.

Potentiometric Sensor for the High Throughput Determination of Tetramisole Hydrochloride

The electrochemical response characteristics of poly(vinyl)chloride (PVC) based membrane sensors for determination of tetramisole hydrochloride (TmCl) is described. The membranes of these electrodes consist of tetramisole-tetraphenyl borate (Tm-TPB), chlorophenyl borate (Tm-ClPB), and phosphotungstate (Tm(3)-PT) ion associations dispersed in a PVC matrix with dibutylpthalate as a plasticizer. The electrodes were fully characterized in terms of composition, life span, usable pH range, and working concentration range and ionic strength. The electrodes showed Nernstian response over the concentration ranges of 7.4 x 10(-7) to 1.0 x 10(-2) M, 1.7 x 10(-6) to 1.0 x 10(-2) M, and 5.6 x 10(-6) to 1.0 x 10(-2) M TmCl, respectively, and were applied to the potentiometric determination of tetramisole ion in pure solutions and pharmaceutical preparations. The potentiometric determination was also used in the determination of tetramisole in pharmaceutical preparations in four batches of different expiration dates. The electrodes exhibited good selectivity for TmCl with respect to a large number of excipients such as inorganic cations, organic cations, amino acids, and sugars. The solubility product of the ion-pair and the formation constant of the precipitation reaction leading to the ion-pair formation were determined conductometrically. The new potentiometric method offers the advantages of high-throughput determination, simplicity, accuracy, automation feasibility, and applicability to turbid and colored sample solutions.