Chapter Four – Sample Processing

This chapter is devoted to sample processing, which plays a key role in the ultimate success of any detection technology. Many of the techniques discussed in the following chapters process from microliter to a few milliliter, whereas it may be necessary to sample hundreds of milliliter to thousands of liters. In this chapter the need for sample processing is justified, and different methods of sampling are presented. Subsequently, the chapter introduces different methods of sampling and gives an introduction to the basic processes behind different sample processing techniques. The chapter is organized according to process order. First, initial methods of concentration are presented followed by secondary concentration steps, which further reduce the volume and in some cases isolate the pathogen of interest. There is some overlap between techniques used in these stages. Next, a section is devoted to the extraction of nucleic acids for detection by molecular methods. Analytical controls are important to determine how well a process is working, in terms of recovery rate, and different approaches to this are discussed. The chapter concludes with a summary identifying what has thus far been achieved in the area of sample processing, what has so far been neglected, and what needs to be done.