Robustness studies Analysis of formulation The developed

The robustness of a method is the ability to remain unaffected by small changes in chromatographic parameters. The experimental conditions were purposely altered and the chromatographic resolution of PHE, PAR, CAF, CET and NIM was assessed. The chromatographic parameters included variation of flow rate second deliberate change was made by change in TAK-901 and third was deliberate change in detection wavelength. To study the effect of flow rate on system suitability parameters ±10% change on either side of actual flow rate was made i.e., from 1.0 to 1.1 mL/min and 0.9 mL/min, while other conditions were held constant. For experiment to study the effect of pH on system suitability parameters change in pH of ±0.1 units on either side of actual pH of buffer was made i.e., from 3.3 to 3.4 and 3.2 while other chromatographic conditions were kept constant. For variation of detecting wavelength change in detecting wavelength of ±5 nm was made and system suitability parameters were recorded. All the robustness studies were carried using a mix standard having resultant concentration of 10 μg/ml for PHE, 325 μg/ml for PAR, 25 μg/ml for CAF, 5 μg/ml for CET and 100 μg/ml of NIM. The system suitability parameters considered for deliberate changes were %RSD of peak areas, mean tailing factor and mean retention time.