Charge Transfer Complexes of Gamma Aminobutyric Acid-Analogue, A Neurotransmitter: Synthesis and Spectrophotometric Determination

Abstract

Here, we report spectrophotometric method for the determination of gabapentin through charge transfer complexes with σ and π acceptors and also with dye stuffs. The method involves ion-pair complex formation of gabapentin with ninhydrin, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, tetracyanoethylene, methyl orange and picric acid. The optimum conditions for the reactions and validation of described procedure have been studied. Resulting complexes absorb at 580, 315, 340, 464 and 342 nm in the Beer's law range of 2-22, 32-80, 40-360, 12-96 and 15-135 µg mL-1 with correlation coefficient greater than 0.998 in each case respectively. The proposed method was applied successfully for the determination of gabapentin in pharmaceutical formulations. Satisfactory recovery values suggest that the method is reliable for the determination of gabapentin in pharmaceutical formulations without interference of excipients. In addition, the spectral characteristics including oscillator's strength, dipole moment, ionization potential, energy of complexes, resonance energy and also the thermodynamic parameters i.e. association constant and Gibb's free energy changes have been determined. Benesi-Hildebrand plots for each complex have been constructed. Further, solid charge transfer complexes of gabapentin were synthesized and characterized by IR spectroscopy.

Pregabalin and Tranexamic Acid Evaluation by Two Simple and Sensitive Spectrophotometric Methods

“…Water was used to prepare stock solution of PG and TXA because of the free solubility of the drugs and working range solutions were prepared in acetonitrile. It has been known that methanol interferes in charge transfer complex formation so acetonitrile was used in working range solutions in subsequent analysis [ 25 ]. Dichloromethane was found to be suitable for preparation of DNP and TNP solutions.…”

The Use of Chloranilic Acid for the Spectrophotometric Determination of Three Macrolides through Charge Transfer Complex

“…In the last decade, a number of spectrophotometric methods for the determination of verapamil [17], gabapentin [18], quinolone antibiotics [19], metformin [20], ascorbic acid [21] and montelukast [22] have been developed by our research fellows. In the present study we aimed to describe the rapid and accurate spectrophotometric methods for the determination of three macrolides; ERY, roxithromycin (ROX) and CLR.…”