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HOW IT WORKS
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polar blue dye will have a stronger partition affinity for the stationary phase.
The more polar red dye favors the mobile phase, moves more rapidly down
the column than the blue dye, and emerges first from the column into the
detector. If we could see into the column we would see a purple disc move
down the column, gradually separating into a fast moving red disc followed by
a slower moving blue disc (Fig. 1.3).
1.1.2
Basic Hardware: A Quick, First Look
The simplest HPLC system is made up of a high-pressure solvent pump, an
injector, a column, a detector, and a data recorder (Fig. 1.4).
Note: The high pressures referred to are of the order of 2000–6000 psi. Since
we are working with liquids instead of gases, high pressures do not pose an
explosion hazard. Leaks occur on overpressurizing; the worse problems to be
expected are drips, streams, and puddles.
Solvent (mobile phase) from a solvent reservoir is pulled up the solvent
inlet line into the pump head through a one-way check valve. Pressurized in
Figure 1.3
Separation model 2 (HPLC column).
Figure 1.4
An isocratic HPLC system.