Advanced Gradient System

For optimum functionality in automated systems designed primarily for reversed-phase chromatography and other gradient techniques, an advanced-gradient system is recommended. Key features include  

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Four basic types of elution are used in HPLC, namely, the isocratic system, the basic gradient system, the inert system and the advanced gradient system (see Figure 1.1). The most commonly used detectors are those based on spectroscopy in the region 185-400 nm, visible-ultraviolet (UV) spectroscopy in the region 185-900 nm, post-column derivatisation with fluorescence detection (see next), conductivity [7] and multiple wavelength UV detectors using a diode array system detector (see next). Other types of detectors available are those based on electrochemical principles, refractive index, differential viscosity, and mass detection [8]. 

For gas phase heterogeneous catalytic reactions, the continuous-flow integral catalytic reactors with packed catalyst bed have been exclusively used [61-91]. Continuous or short pulsed-radiation (milliseconds) was applied in catalytic studies (see Sect. 10.3.2). To avoid the creation of temperature gradients in the catalyst bed, a single-mode radiation system can be recommended. A typical example of the most advanced laboratory-scale microwave, continuous single-mode catalytic reactor has been described by Roussy et al. [79] and is shown in Figs. 10.4 and... 

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