Sample Preparation

This chapter discusses the principles and fundamentals of some of the most important bioanalytical sample preparation techniques, namely, protein precipitation (PPT), liquid-liquid extraction (LLE), and solid-phase extraction (SPE). It also discusses those cases where sample preparation can be circumvented. The chapter presents a short discussion of alternative sample preparation approaches, and a discussion about some of the new technologies emerging in the field of bioanalytical chemistry. Today, liquid chromatography–mass spectrometry (LC-MS) and gas chromatography–mass spectrometry (GC-MS) instruments provide very high sensitivity, and pre-concentration has become less important for many bioanalytical applications. However, if a concentration step is included in the sample preparation, it is still an advantage as this may increase the reliability in detection. In general, sampling and sample preparation constitute over 80% of the total analysis time, and these steps are highly important for the overall success of the bioanalytical measurement.