Spectrophotometric Determination of Allopurinol Drug in Tablets: Spectroscopic Characterization of the Solid CT Complexes

Abstract

Spectrophotometric micro determination of allopurinol (ALP) via charge-transfer formation is described. This includes the utility of some π-acceptors such as 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and 3,6-dichloro-2,5-dihydroxy-p-benzoquinone (p-CLA) for estimation of ALP drug (act as è-donor). These reactions are applied for determination of ALP in its pharmaceutical preparations coming from different companies. Elucidation of the chemical structure of the solid CT complexes formed via reaction between drugs under study and π-acceptors, using elemental analyses (C, H, N), I. R., 1 H NMR and mass spectrometry.

A Brief Review of Analytical Methods for the Estimation of Allopurinol in Pharmaceutical Formulation and Biological Matrices

“…The LOD was 7.96 μ g mL –1 and 1.70 μ g mL –1 for ALLP-DDQ and ALLP-p-CLA CT complexes, respectively. LOQ was 26.53 μ g mL –1 and 5.68 μ g mL –1 for ALLP-DDQ and ALLP-p-CLA CT complexes, respectively [ 18 ].…”

IR, 1H NMR, mass, XRD and TGA/DTA investigations on the ciprofloxacin/iodine charge-transfer complex

“…In continuation of our earlier studies on the trend of chargetransfer complexes using drugs as donors [21][22][23][24], herein, we reported the spectroscopic investigation on the molecular complexes of ciprofloxacin (CIP) antibiotic drug with iodine (I 2 ) as sigma acceptor. This target aimed to using spectroscopic characterization to suggest the mechanism of interaction of CIP drug with iodine.…”

Charge transfer interaction of organic p-acceptors with the anti-hyperuricemic drug allopurinol: Insights from IR, Raman, 1H NMR and 13C NMR spectroscopies

“…Instead, Allop contains high electron density over the pyrazole ring (20)(21)(22). H NMR spectrum of free Allop, the proton of the pyrimidine ring N-H was observed as a singlet signal at 3.84 ppm, and that of pyrazole ring N-H appeared as a singlet at 12.87 ppm (18). The signal due to the phenolic proton (-OH) of the PA acceptor, which is observed at d ~11.94 ppm (10) in the spectrum of the free PA acceptor, is no longer observed.…”

“…In a previous study, we found that Allop forms a yellow solid complex with DDQ in acetonitrile via 1:1 interaction, and the CT interaction occurs through n-p* transition with deprotonation of NH group of Allop, to only one of the CN groups of DDQ, by forming intermolecular hydrogen bonding (18). In this study, however, Allop forms a reddishbrown solid complex with DDQ in methanol-chloroform mixture, but the IR data indicate that the interaction occurs through p®p* transition via the pyrazole ring of Allop and the aromatic ring of DDQ.…”

“…For example, the interactions between theophylline (10) and metronidazole (17) with different types of σ-and π-acceptors were studied. In our previous study, we determined the content of Allop in some pharmaceutical preparations spectrophotometrically via CT interaction between Allop and 3,6-dichloro-2,5-dihydroxy-p-benzoquinone and 2,3-dichloro-5,6-dicyano-p-benzoquinone in acetonitrile (18).…”