Measurement of recoveries and physical properties of model formulations with different methods of adding active ingredients to blank samples

A sample preparation method for measuring recovery is to add the active ingredient of a solution or standard to a solid blank sample. Model formulations were prepared by various addition methods, and recoveries and physical properties were measured. The results showed no differences in the recoveries depending on the addition method, but the variabilities and physical properties differed. It was suggested that the most appropriate method was to add ≥50 mg/batch when the standard was added directly, or ≥2 mL/batch when the solution was added (solvent was removed), followed by grinding.