Comparative Study of Different Plasticized Membrane Electrodes for the Stability-indicative Determination of Torsemide

Abstract

Four torsemide-selective electrodes all on solid state graphite support were developed and characterized in polyvinylchloride matrices. Precipitation-based technique with tetraphenylborate (TPB) as an electroactive material in polyvinylchloride (PVC) matrix was used for sensor 1 fabrication without incorporation of an ionophore. 2hydroxypropyl-β-cyclodextrin (HP-β-CD) based technique with tetraphenylborate and either dioctyl phatalate (DOP), dibutyl sebasate (DBS) or 2-nitrophenyl octyl ether (o-NPOE) as plastisizer in carboxylated polyvinylchloride (PVC-COOH) matrix were used for sensor 2, 3 and 4 fabrications, respectively. Fast and stable Nernstian responses were evaluated according to IUPAC recommendations in the concentration ranges from 1x10-5 to 1 x 10-3 M for sensor 1 , from 1x10-5 to 1x 10-2 M for sensor 2, from 1x10-6 to 1 x 10-4 M for sensor 3, and from 1x10-6 to 1 x 10-3 M for sensor 4. The sensors show good selectivity to the drug in presence of a variety of inorganic and organic interferents including acid degradation product of torsemide, related substances and pharmaceutical excipients. Validation of the method showed the suitability of the proposed electrodes for the use in the quality control assessment of the drug. Furthermore, statistical comparison between the results obtained by the proposed method and the official method of the drug was performed and no significant difference was found.

Development and validation of stability-indicating methods for determination of torsemide

“…The degradation process under the previously mentioned conditions was followed using TLC and HPLC. It was found that all conditions produce the same two degradation products, Figure 1, which confirms the already existing analytical data [22][23][24]; one of them (deg 1) is among the impurities stated in USP and BP (impurity B), while the other degradation product is an aliphatic fragment with no considerable UV absorption (deg 2) [24]. Therefore, it is essential to develop analytical procedure which will serve a reliable, accurate and sensitive stability indicating method for the determination of TOR in presence of its degradation products (related impurity B).…”

“…The non-pharmacopoeial methods used for determination of TOR include HPLC [5][6][7][8][9], LC/MS [10][11][12][13], GC/MS [14,15], spectrophotometry [16][17][18][19][20] and TLC-densitometry [21]. Stability-indicating HPTLC [22], HPLC [23] and ion selective electrode [24] methods have been recently reported for analysis of TOR but no spectrophotometric studies were performed.…”

“…According to the literatures in hands, all the described methods lake the inherent stability studies, exceptionally two chromatographic recently published methods [22][23][24]. The HPLC method depends on sophisticated gradient elution program due to less suitable chromatographic conditions [23], while, the TLC method offers a narrow quantitative range for pharmaceutical application [22].…”

Potentiometric sensors for the determination of pharmaceutical drugs

“…The potentiometric response was linear over a drug concentration range of 1×10 -6 -1×10 -2 M. The established electrochemical approach has been effectively employed for the detection of PR in the pure state, pregabalin capsules and human plasma without any interference. For the quality control assessment of torasemide (TOS), four TOS-selective electrodes were established and characterized in PVC matrices 58 . Precipitation-based approach with TPB as an electroactive substance in Furthermore, the OL sensor was employed for the quantification of the OL in human plasma with an average recovery of 99.49%.…”