Author : Hayam Lotfy
CoAuthors : Dalia Mohamed, Shereen Mowaka.
Source : Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Date of Publication : 01/2015
Abstract : Simple, specific, accurate and precise spectrophotometric methods were developed and validated for the
simultaneous determination of the oral antidiabetic drugs; sitagliptin phosphate (STG) and metformin
hydrochloride (MET) in combined pharmaceutical formulations. Three methods were manipulating ratio
spectra namely; ratio difference (RD), ratio subtraction (RS) and a novel approach of induced amplitude
modulation (IAM) methods. The first two methods were used for determination of STG, while MET was
directly determined by measuring its absorbance at kmax 232 nm. However, (IAM) was used for the simultaneous
determination of both drugs. Moreover, another three methods were developed based on derivative
spectroscopy followed by mathematical manipulation steps namely; amplitude factor (P-factor),
amplitude subtraction (AS) and modified amplitude subtraction (MAS). In addition, in this work the novel
sample enrichment technique named spectrum addition was adopted. The proposed spectrophotometric
methods did not require any preliminary separation step. The accuracy, precision and linearity ranges of
the proposed methods were determined. The selectivity of the developed methods was investigated by
analyzing laboratory prepared mixtures of the drugs and their combined pharmaceutical formulations.
Standard deviation values were less than 1.5 in the assay of raw materials and tablets. The obtained
results were statistically compared to that of a reported spectrophotometric method. The statistical comparison
showed that there was no significant difference between the proposed methods and the reported
one regarding both accuracy and precision.
Download PDF