ABSTRACT
This chapter discusses of manual and automated sample preparation procedures for pharmaceutical formulations. Yet, a number of methods in the United States pharmacopeia describe the use of open-column methods for sample pretreatment. Analytichem International (now Varian Sample Preparation Products) introduced their Chem-Elut cartridges in the mid-1970s using diatomaceous earth as packing material. Throughout the 1980s, solid-phase extraction cartridges packed with a variety of materials exhibiting a wide range of chemistries were formulated and marketed. As in analytical liquid chromatography, analyte retention depends on sample concentration, solvent strength, and sorbent characteristics. An empirical approach to methods development initially involves screening the available sorbents. Analytical procedures which traditionally have been viewed as very different and are often carried out in different laboratories, for example, the analysis of drugs in parenteral formulations and the analysis of drugs and metabolites in body fluids, if viewed in terms of the unit operations involved, become essentially identical operations.
