Derivative spectrophotometric analysis of benzophenone (as an impurity) in phenytoin

Abstract

Three simple and rapid spectrophotometric methods were developed for detection and trace determination of benzophenone (the main impurity) in phenytoin bulk powder and pharmaceutical formulations. The first method, zero-crossing first derivative spectrophotometry, depends on measuring the first derivative trough values at 257.6 nm for benzophenone. The second method, zero-crossing third derivative spectrophotometry, depends on measuring the third derivative peak values at 263.2 nm. The third method, ratio first derivative spectrophotometry, depends on measuring the peak amplitudes of the first derivative of the ratio spectra (the spectra of benzophenone divided by the spectrum of 5.0 μg/mL phenytoin solution) at 272 nm. The calibration graphs were linear over the range of 1-10 μg/mL. The detection limits of the first and the third derivative methods were found to be 0.04 μg/mL and 0.11 μg/mL and the quantitation limits were 0.13 μg/mL and 0.34 μg/mL, respectively, while for the ratio derivative method, the detection limit was 0.06 μg/mL and the quantitation limit was 0.18 μg/mL. The proposed methods were applied successfully to the assay of the studied drug in phenytoin bulk powder and certain pharmaceutical preparations. The results were statistically compared to those obtained using a polarographic method and were found to be in good agreement.

A Validated UV Spectroscopic Method for Simultaneous Determination of Benzil and Benzophenone Impurities in Phenytoin Sodium

“…United States Pharmacopoeia (USP) has recommended HPLC method for the determination of benzophenone as main impurity in phenytoin 4 . A polarographic and a derivative spectrophotometric method have been used for the determination of benzophenone, as an impurity, in phenytoin [14][15] . However, no methods could be found for the simultaneous determination of phenytoin along with two of its potential impurities, benzophenone and benzil.…”

Molecular Structure of Phenytoin: NMR, UV-Vis and Quantum Chemical Calculations

“…[15] Previously, UV-Vis measurements were used for determining the phenytoin quantity alone [16,17] or in the presence of other drugs. [18,19] Moreover, such data give information about the solubility in different solvents. [20,21] Also, NMR measurements were used to study DPH in solution [22][23][24] and its binding to model peptide corresponding to a segment of sodium channel.…”

Validated Spectrophotometric Methods for Simultaneous Determination of Food Colorants and Sweeteners

“…The aim of this work is to develop easy, sensitive, and fast spectrophotometric methods that can be applied for the routine analysis of the colorants (BB and IND) and sweeteners (ASP and ACE-K) simultaneously in the quaternary laboratory mixtures, foods, and drinks without previous separation. In the present study, measurements were assayed zero-crossing and ratio spectra derivative techniques [34][35][36]. Two methods were successfully applied for the above combination, and satisfactory results were obtained.…”