Pickering Laboratories Pinnacle PCX - Page 19

1.3
Section 1
IntroductIon
Pinnacle Operators Manual
Pickering Laboratories Inc.
In order to understand post-column HPLC, we need to understand the design of an HPLC. If we connect an
HPLC pump directly to a detector (with nothing in between), the baseline from the detector shows a periodic
noise (Figure 1-1); the time period is equivalent to the pump stroke.
Now add a commercial pulse dampener. The baseline is still not smooth; the periodic noise is still there
although less pronounced (Figure 1- 2). The pulse dampener absorbs most of the pulses from the pump, but
the flow requires more stabilization.
A restriction inline will cause the flow at the outlet of the restriction to be constant. In an HPLC system, this is
accomplished with the analytical column. Actually, the column does more than separation; it creates a back-
pressure. It is the combination of the pulse dampener and the column that creates a smooth baseline.
(Figure 1-3)
Eluants
LC Pump
Injector
Detector
Waste
Baseline
Eluants
LC Pump
Injector
Detector
Waste
Baseline
Commmercial
Pulse
Dampener
(capacitor)
FIGURE 1-1
FIGURE 1-2