Simple Spectrophotometric Methods for the Simultaneous Determination of Pseudoephedrine and Loratadine in Bulk and Tablet Forms

Abstract

Two simple, accurate and precise spectrophotometric methods were developed for the
simultaneous determination of pseudoephedrine sulphate and loratadine in bulk and
tablets. Absorbance factor and absorbance correction methods are proposed in this study.
The two methods are principally exploit the spectral characteristics of the two compounds
to affect mathematical manipulation of Beer’s law. The approach in the two methods
enabled removal of the spectral interference from loratadine at the wavelength for the
determination of pseudoephedrine, hence it was possible to the determine pseudoephedrine
in the presence of loratadine using two wavelengths (257 nm and 280 nm). Beer’s law was
obeyed in the concentration ranges of 140-860 μg/ml and 6-36 μg/ml with correlation
coefficients (R2) 0.9998 and 0.9999 for pseudoephedrine and loratadine, respectively. The
accuracy and the precision of the proposed methods were very good with percent relative
standard deviation (%RSD) ˂ 2% being in agreement with International Council on
Harmonization guidelines. The analysis of variance (ANOVA) test confirmed the validity of
the proposed methods and their comparability with a reported method, as indicated by p
values greater than 0.05. The p-values obtained were 0.385 for loratadine and 0.692 for
pseudoephedrine sulfate, demonstrating no significant difference between the methods and
supporting their accuracy and reliability. The low limits of detection (LOD) of 0.6891 µg/ml
for loratadine and 46.7172 µg/ml for pseudoephedrine sulfate confirm the high sensitivity
of the proposed methods, making them suitable for precise quantitative analysis.