Four µm columns separate analytes with greater efficiency, permitting the use of higher
flow rates while maintaining resolution and reducing overall run time. Running any
column at increased flow rates may cause a decrease in peak resolution. However, the
superior chromatographic fidelity achieved using the new 4 µm columns, including the
Dionex IonPac AS11-HC-4µm, Dionex IonPac AS18-4µm, and Dionex IonPac CS19-
4µm, minimizes such losses, to provide better separation of ions in complex matrices.
Faster flow rates reduce run time and increases productivity when multiple samples are
being analyzed, but back pressure is also increased, which is typically >3000 psi. To
take advantage of the benefits of 4 µm columns, they should be combined with a highpressure
instrument, such as the Dionex ICS-5000+ HPIC system, which can operate
continuously at up to 5000 psi using eluent generation
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