Empower Tip: Empower CDS User Question

In this tip for Empower Chromatography Data System (CDS), we will answer an Empower CDS user question. In the last tip, we explored the difference between Amount and Concentration. Tip 270.

Q: How can I get Empower to calculate isoelectric point (pI) when using the Maurice to do capillary isoelectric focusing (cIEF) to separate proteins by charge?

Great question. This scenario involves using two pI markers and Custom Fields to calculate pI for the peaks in between the markers. Please remember to validate all Custom Fields before using them to generate final reportable results.

The information for the markers is entered in the ‘Instrument Method Editor’ under the ‘Markers’ section.

Enter the values for the makers in the ‘Component Editor’ on the ‘Value’ tab.

Custom Fields

The properties of the Custom Field PI_Calc and the full equation can be seen in figures 3 and 4.

[figures 3 & 4]

The properties of the Custom Field PI_Slope can be seen in figure 5.

The properties of the Custom Field PI_Unknown can be seen in figure 6.

The properties of the Custom Field PI_Y_Intercept can be seen in figure 7.

The properties of the Custom Field PI_Value can be seen in figure 8.

Processing Method and Results

Enter the names of the markers in the Processing Method on the ‘Components’ tab. These names must match the ones in the Custom Fields. If you decide to create an LC Processing Method and use Retention Time rather than a CE Processing Method with Migration Time, you will need to adjust the Custom Fields accordingly.

The calculated result with all fields populated can be seen in figure 10.

It’s that easy!