Antec Scientific DECADE II 171, User Manual, Page: 41 / 87

CHAPTER 5
Noise suppression: ADF™
41
This is further illustrated by an overlay of the same chromatographic peak
with a sine of 0.07 Hz (Fig. 21).
Fig. 21. Overlay of a chromatographic peak with 0.07 Hz sine.
Typically in chromatography narrow peaks are in front of a chromatogram
while peaks with longer retention times get wider. As a consequence
frequencies are not constant but vary between 0.1
– 0.01 Hz, which
corresponds to 10
– 100 s peak width.
Fig. 22. Typical chromatogram with peak widths between 10
– 100 s..
Noise in chromatography can come from different sources. Pump pulsations
are typically shown as a very regular noise pattern, while electronic noise has
a more random character. This is illustrated in Fig. 23 where a noise trace is
shown with an overlay of a 10 and 0.4 Hz sine.
40000
140000
240000
340000
440000
540000
3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0
ADF
-2000
98000
198000
298000
398000
498000
598000
698000
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0
min
h
40 s
0.025 Hz 10 s
0.10 Hz