Synthesis and spectrophotometric determination ibuprofen charge transfer complexes with p-chloranil, 7,7,8,8-tetracyanoquinodimethane, bromothymol blue, methyl orange and picric acid

Abstract

Three simple, sensitive and inexpensive spectrophotometric methods have been described for the assay of ibuprofen in bulk drugs and pharmaceutical formulations. The developed methods are based on the formation of colored charge transfer complexes of ibuprofen with p-chloranil, 7,7,8,8-tetracyanoquinodimethane, bromothymol blue, methyl orange and picric acid in acetonitrile as solvent. These newly formed complexes were found to absorb at 438, 394, 403, 418, 374 nm respectively. Optimizations of various experimental conditions are described. Beer's law obeyed in the concentration range6-54, 2-24, 4-28, 3-21 and 4-28 μgmL-1 with correlation coefficient >0.998 in each case and lower limit of detection values were 76, 90, 234, 63 and 189 ng mL-1, respectively. The association constants and standard free energy changes were studied using Benesi-Hildebrand plots. Oscillator's strength, ionization potential and energy of complexes in the ground state for all the complexes have been calculated. For further confirmation, solid charge transfer complexes were synthesized and characterized by IR and 1H-NMR spectroscopy. The applicability of the method was demonstrated by the determination of studied drugs in commercial tablets with satisfactory results. No interference from excipients was observed in the formulations. © 2013 Sultana N, et al.