Study of 7,7′,8,8′-Tetracyanoquinodimethane Charge Transfer Complexes with Some Lone-Pair-Donating Drugs

Abstract

The interaction between 7,7',8,8'-tetracyanoquinodimethane (TCNQ) and oxamniquine (I), azithromycin (II), omeprazole (III), pantoprazole (IV), and benzydamine hydrochloride (V) was investigated. The reaction conditions were optimized to obtain typical charge transfer complexes (CTC). The nature of the formed complexes was proved by thorough study of the thermodynamic parameters namely delta G (free energy), delta H (enthalpy), and delta S (entropy). The association constant KcAD and the molar absorptivity xi lambda AD of the formed complexes were determined using the Benesi-Hildbrand equation. The effect of temperature on these constants gave evidence of CTC formation. The reaction of TCNQ with I-V was found to be in 1:1; as being determined by the Foster method. Spectrophotometric measurements of the formed CTC were used for the quantitative determination of the studied drugs in both pure or pharmaceutical formulation. The mean percentage recoveries were 99.17 +/- 0.34, 99.75 +/- 0.12, 100.52 +/- 0.41, 98.75 +/- 0.63, and 99.23 +/- 62 for I, II, III, IV, and V, respectively. There was no significant difference observed when the method was statistically compared with the official and reference methods used to determine these drugs.

Differential pulse anodic voltammetric determination of pantoprazole in pharmaceutical dosage forms and human plasma using glassy carbon electrode

“…Many analytical methods for the quantitative determination of pantoprazole in pharmaceutial formulations and biological fluids have been reported [3][4][5][6][7][8][9]. Electrochemical methods, such as cyclic voltammetry (CV) 1 , linear sweep voltammetry, and differential pulse voltammetry (DPV), have been widely applied for the determination of compounds of pharmaceutical interest [10][11][12][13][14][15][16][17].…”

Determination of Pantoprazole in Pharmaceutical Formulations and Human Plasma by Square‐Wave Voltammetry

“…Methods for the determination of P in pharmaceutical formulations and in biological materials that have been reported previously included high performance liquid chromatography (HPLC) (Cass et al 2001;Mansour and Sorour 2001;Tanaka et al 1995;Jiao et al 1999;Tanaka and Yamazaki 1996;Ekpe and Jacobsen 1999), capillary electrophoresis (Tivesten et al 1999;Daniela et al 1997), spectrophotometric methods (Azza 2000;Bebawy et al 1997;Wahbi et al 2002), and electrochemical methods (Radi 2003a(Radi , 2003b. The present work was concerned with the study of the electrochemical behavior of P and to develop a new, rapid, and sensitive method of Osteryoung square-wave voltammetry (OSWV), at hanging mercury drop electrode (HMDE) for its determination in pharmaceutical formulations and also applying it to human plasma, including spiked P and plasma of patients orally administered P. The validation parameters such as sensitivity, accuracy, precision, and recovery of the method were evaluated.…”

Spectrofluorimetric and Spectrophotometric Determination of Oxamniquine in Pharmaceuticals and Biological Fluids via Derivatization with 4‐Chloro‐7‐Nitrobenzo‐2‐oxa‐1,3‐Diazole (NBD‐Cl)

“…1). These methods include: spectrophotometry, [3][4][5] non-aqueous titration, 6 gas chromatography, 7 HPLC, [8][9][10][11][12][13] capillary electrophoresis, 11 polarography, 14 flow injection analysis, 15 and fluorimetry. The oral bioavailability of oxamniquine is good, and effective plasma levels are achieved in 1-1.5 h. 1 Oxamniquine is the subject of a monograph in the USP (XXIII), 2 whereby a spectrophotometric method is recommended for its determination, whether in its pure form or in capsules.…”