Various chromatographic conditions were experienced to develop the stability-indicating LC method. The UPLC method was optimized through the assessment of different buffers and organic solvents. The use of 0.002M of dipotassium hydrogen phosphate and acetonitrile in a ratio of 53:47%v/v on BEH C18; 50×2.1mm; 1.7µm column was found to furnish sharp, well-defined peak with good resolution and low retention time of about 2.69 min at a flow rate 0.6 ml/min. The peak was monitored at 210nm.
After equilibration of the column with mobile phase, five replicate injections of 2.0?l of standard solution through an autosampler injector were injected and the chromatograms were recorded. The system suitability parameters were calculated and results are shown in Table 2. The results have been confirmed with respect to %RSD, resolution and USP tailing factor. The %RSD was less than 1. The results will make sure transferability of the method and raise the reliability of the results obtained.
The results of the degradation studies state the specificity of the method as there was no interference from the sample, placebo and degrading peaks and also reveal that the method was selective and stability-indicating. The % assay of the drug was calculated after exposure of Erythromycin estolate solutions to different stress conditions. The drug undergoes degradation of oxidative and thermal/humidity stress conditions. The degrading peaks were well resolved from the drug peak. The drug was stable in thermal and photolytic conditions.