How can I develop a flow program for an unknown sample for the Eclipse FFF?

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The VISION CHS software for the Eclipse offers a simulation mode in its SCOUT DPS processing module. To use the simulation mode, click on the SCOUT DPS tile.

Once SCOUT comes up, go to the INSERT menu and click on ADD NEW to insert a new simulation node.

Setting up a Virtual Experiment

1. Enter the sample and method parameters on the right-hand side. The plot shows the simulated fractogram which is updated with every change made to the parameters.

2. In the Sample & Experiment Tab enter a set of at least three sizes which represent your sample:

a) the smallest size you want to separate
b) the main population
c) the largest size of interest
You can enter a description and a mass fraction for each peak.

3. Set appropriate parameters in the Solvent Properties and Inject sections.

4. Select the separation device, then enter a flow program in the Time Table & Flows tab. This is identical to the flow program used in VOYAGER to run an experiment.

You will note that with each entry, the fractogram plot updated to reflect the changes. With immediate visual feedback it is easy to modify the program until a satisfactory result has been achieved.

Optimizing the Parameters

There are two approaches to optimizing the fractogram. One is to stay with the same virtual experiment and observe how the results change until optimal separation has been achieved. The second is to create additional virtual experiment(s) and compare different set of parameters side-by-side.

To create an additional virtual experiment for comparison, Press the Add Virtual Experiment Button. A copy will be created and appear in the Results. Select the copy to modify it.

You can then toggle between the two virtual experiments by clicking on each one in the results to change parameters or compare Fractogram Simulations. The results table allows you to compare the results from both virtual experiments side-by-side. In the example shown below, we’ve named our copy “Using Gradient” and changed the cross-flow to an exponential decay to decrease elution of the aggregate peak.

Similarly, you can explore the effect of changing the spacer height, the temperature, or any other parameter of the experiment.
The Fractogram Simulation node is saved with the SCOUT datafile for later reference.

For further reading:
Field-Flow Fractionation: Virtual Optimization for Versatile Separation Methods
TN6005 - Eclipse Aqueous Method Development Quick Start Guide

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