Influence of adsorption during grinding on the analytical quantification of active ingredients in medicinal products

Abstract

Sample preparation is a major process in analysis, consisting of the necessary operations needed to modify the sample for subsequent delivery of the analytes in a convenient form for analysis. Despite the fact that the proper execution of sample preparation is paramount in achieving accurate quantitation, it is generally not the focus of attention in discussing pharmaceutical analytical methods. Grinding is common practice to reduce particle size and homogenize the sample; however, when under physical contact with the interface, particles are subject to a number of interactions. Forces such as van der Waals forces, electrostatic forces, and valency forces at the surface, which are normally insignificant, become prominent during grinding, and may be sufficient to cause adsorption of molecules at the surface of a particle. The objective of this study was to investigate the influence of adsorption of active pharmaceutical ingredients during grinding of tablets for assay testing of drug products. It was investigated whether ceramic, glass and stainless steel surfaces, each represented by a pestle and mortar, influenced the assay values of simvastatin, alendronate sodium and perindopril erbumine active ingredients.