Figure 15–5: Normalized peak height of dopamine as a function of spacing setting (red
curve) based on chromatograms recorded with a 100 nM standard of catecholamines in 10
mM HAc with a SenCell
The dotted curve is a simulated curve based on the Cotrell equation (F.G. Cottrell, Z. Phys. Chem
42 (1903) 385).
Decreasing the spacing/working volume is limited by an increased pressure drop over the flow
cell that will eventually lead to an obstruction of the flow. The onset is typically characterized by
an increased noise level and a rise in system back pressure.
Warning:
Applying low working volume settings should be done with great care
because it may cause excessive pressure buildup over the flow cell, excessive baseline
noise, and damage to the cell. Do not operate the cell at position 0.
It is evident that noise remains relatively constant as a function of spacing, but at a spacing of
approximately 6 µm a significant increase in noise is observed, accompanied by a rise in system
pressure as a restriction builds over the cell. So in this example, setting the cell spacing less than
approximately 12 µm is not advisable.
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