Get Empowered: Review Window and the Processing Method | Tip #126, GPC/SEC Data
Tip #126: Working with GPC/SEC data in Empower Software (Part 3)
Welcome back to Get Empowered! In the last Empower tip-of-the-week post for Empower Chromatography Data Software, we learned about the results generated using a Processing Method that specifies relative calibration when working with narrow standards (Tip #125).
In this week’s tip, we are going to learn about using a Processing Method for relative calibration working with broad standards. The advantages to this technique are, it is easy and accurate for polymers of the same chemical nature as the standards. The disadvantages are broad standards are not available for every type of polymer and a single broad standard covers a limited molecular weight range.
Let’s get started.
Within Alter Sample I, select the Broad Standard and click the ‘Amounts tool’. Select the Moments tab and enter the Mn, Mw, Mz and Mz+1. These values should be available from the supplier of the standard or can be determined experimentally (figure 1).
The Processing Method developed in the earlier tip for Relative Calibration (Tip #125) can be used in this case. Once the data has been processed, we can review the results for the broad standard in Review. The Mn, Mw, Mz and Mz+1 are the same as entered in step 1 (figure 2).
In this example, the calibration curve has 10 points. The standard was injected twice, and we entered the 4 moments giving us 8 points plus Empower determines the Mp for each injection as well for a total of 10 points (figure 3).
Here is a sample with its corresponding results based on the new calibration curve (figure 4).
We see the slice table and distribution plot for the sample (figure 5).
Finally, here is an overlay of the distribution plots for the same sample where we used the narrow standards versus the broad standard to generate the calibration curve. The differences in the numbers are to be expected as the calibration curves generated in each case are different (figure 6).
It’s that easy!
- You can use a combination of a broad standard and narrow standards to extend the range of the calibration curve. In this case you may want to add Relative Weighting as can be seen in figure 1. This weights the curve towards the broad standard or the narrow standards. The default value is 1 for all.
- This procedure can be followed using the QuickStart or Pro interface.
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Next week in Empower Tip #127 – We will continue with the series on working with GPC/SEC data in Empower (Part 4).
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