ABSTRACT
The search for higher-throughput methods for small molecular analysis has fueled many innovations on the development of high-speed chromatographic techniques [1-5]. According to the van Deemter equation, reducing particle size of the packing materials is a direct and effective way to enhance the column ef ciency (e.g., see Figure 9.1). However, reducing the particle diameter will result in an increase in the column backpressure. One solution to overcome the high backpressure is to adopt a shorter column with small particles (∼3 μm) for rapid separation [6]. Monolithic columns made from a single piece of porous silica gel can be operated at higher ow rates than conventional HPLC columns due to the higher permeability of monolithic silica rods making higher speed separation possible without a noticeable effect on chromatographic resolution [7]. Ultrahigh-pressure performance liquid (UHPLC) is a technical advance that primarily provides greater mobile-phase pressures to counter the high backpressure resulting from stationary phases with sub-2 μm particles. UHPLC offers theoretical advantages in chromatographic resolution, speed, and sensitivity over conventional HPLC systems (see Chapter 8) [4,8-10].
