Simultaneous Estimation of Abacavir Sulfate and Lamivudine in their Combined Dosage Form by First Derivative Zero-Crossing and Ratio First Derivative Spectroscopic Methods

Two simple, sensitive, specific and accurate spectrophotometric
methods are proposed in the present work for the simultaneous
estimation of Abacavir sulfate (ABA) and Lamivudine (LMV) in
their binary mixture. In first derivative zero crossing technique the
absorbances at 234.2 nm (zero crossing point of LMV) were plotted
against the respective concentrations of ABA. Similarly the
absorbances at 287.3 nm (zero crossing point of ABA) were plotted
against the respective concentrations of LMV. For the ratio spectra
first derivative spectrophotometric method, the graphical treatment of
the overlapping spectra depends on division of the absorption
spectrum of the binary mixture by a standard spectrum of one of the
components and then the first derivative amplitudes measured at
233.0nm for ABA and 236.4nm for LMV .The calibration curves
follow Beer’s law in the range of 5 to 30 μg/ml for ABA and 2.5 to
15 μg/ml LMV for both the methods. The methods were successfully
applied to quantify ABA combined with LMV in tablets and
validated accordingly.