Abstract
An isocratic HPLC method and two classical UV spectrophotometric methods i.e first derivative zero crossing point method (FDZCP) and ratio derivative spectrophotometry (RDS) were developed for the simultaneous estimation of Ambrisentan (AMB) and Tadalafil (TAD) in its laboratory sample. The HPLC method was developed using Phenomenex Luna C18 column (250× 4.6 mm i.d., 5 particle size), with mobile phase composition of methanol: acetonitrile: ammonium acetate buffer pH 6.0 (ratio of 35: 30: 35). The flow rate was 1 ml min-1 and effluent was detected at 264 nm. The retention time of AMB was 4.49 minand forTAD 5.97 min. All the three methods were successfully applied for the analysis of laboratory mixture. The recovery for AMB was found to be 100.2-101.18% by HPLC method, 98.19-101.35% by FDZCP method and 99.64-102.09 by RDS method. The recovery for TAD was found to be 98.04-101.63% by HPLC method, 99.73-102.98% by FDZCP method and 100.36-102.11 by RDS method. One way ANOVA was performed and it was found that there is no significance difference between the results of the three methods i.e. the UV spectrophotometric methods were found to be as good as HPLC method and hence any of these methods can be used for the simultaneous estimation of AMB and TAD.
