Understanding The Asm Factor - Agilent Technologies 1290 Infinity II 2D-LC Solution User Manual

2 Concepts of 2D-LC
Active solvent Modulation (ASM)

Understanding the ASM factor

The principle of ASM is diluting
The ASM solution achieves this dilution by a parallel flow of solvents via sample
loop and ASM capillary.
Figure 22
The flow rates F through these parallel capillaries depend on the different
backpressures p of the capillaries in use. The backpressure of a capillary
depends on the capillary length l, radius r to the power of 4, and the viscosity η of
the solvent.
The Hagen-Poiseuille equation describes the relation of these parameters.
2D-LC - User Guide
Principle of active solvent modulation (schematic view)
Hagen-Poiseuille equation
Different ASM capillary lengths have an effect on
the following parameters:
• Capillary back pressure
• Dilution factor
• Optimum dilution for different applications
1
D sample loop solvent with
2
D solvent.
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