Get Empowered: Review Window and the Processing Method | Tip #125, GPC/SEC Data

By June 12, 2019

Tip #125: Working with GPC/SEC data in Empower Software (Part 2)

Welcome back to Get Empowered! In the last Empower tip-of-the-week post for Empower Chromatography Data Software, we learned how to create a Processing Method for Relative Calibration in GPC using narrow standards (Tip #124).

In this week’s tip, we are going to review the results for our calibration curve and the calculated sample molecular weights, along with their molecular weight distributions when using Relative Calibration.

Let’s get started.

Step 1

Once the Sample Set is processed, bring the Result Set into Review. The narrow standards are first in the tree (figure 1).

Empower Tips: The narrow standards are first in the tree | Figure 1

Figure 1

Step 2

Click the Calibration Curve tool to view the Calibration Curve. The R2 indicates we have selected a good fit. There are 18 points on the Calibration Curve because there were three standard vials, each containing a mixture of three narrow standards, and two injections out of each vial (figure 2).

Empower Tips: Click the Calibration Curve tool /view the Calibration Curve | Figure 2

Figure 2

Step 3

Here we can view the result for one of the polymers. We see the Mn, Mw, Mz and Mz+1. The Mp is the molecular weight at the apex of the peak. The polydispersity is Mw/Mn (figure 3).

Empower Tips: View the result for one of the polymers | Figure 3

Figure 3

Step 4

The various molecular weights relate to physical properties of the polymer (figure 4).

Empower Tips: View various molecular weights | Figure 4

Figure 4

Step 5

Click the Results tool to go to the Results Window. Select the Distribution tab to view the slice table. This table shows the molecular weight and log molecular weight for the slices across the distribution. The default is showing all the slices; however, you can change that from the drop-down menu shown (figure 5).

Empower Tips: Select the Distribution tab to view the slice table | Figure 5

Figure 5

Step 6

Click the Distribution Plot tab to view the molecular weight distribution. This shows us where the molecular weights mentioned in Step 3 are taken from and displays the Cumulative % plot overlaid against the distribution. The Cumulative % plot starts at ‘0’ on the far left and ends at ‘100’ on the far right (see the y axis on the right side of the plot). This plot shows us the cumulative % of the polymer at a particular molecular weight as it moves from the high end of the molecular weight distribution to the low-end of the molecular weight distribution. For example, at log mw of 4.92, 70% of the polymer is at or above the value of 4.92 (figure 6).

Empower Tips: Click the Distribution Plot tab/view the molecular weight distribution | Figure 6

Figure 6

Step 7

To compare distribution plots for samples, highlight the results, right click on one, and select ‘View As, Molecular Weight Distributions’. Highlight the distributions for the samples, right click and select ‘Compare’ (figure 7).

Empower tips: Compare distribution plots for samples | Figure 7

Figure 7

Step 8

We now see the overlay of the distributions. The distribution highlighted in the table is the active one in the plot displaying the molecular weights (figure 8).

Empower Tips: See the overlay of the distributions | Figure 8

Figure 8

It’s that easy!

Final note: This procedure can be followed using the QuickStart or Pro interface.


Please rate this Empower Tip of the Week

Next week in Empower Tip #126 – We will continue with the series on working with GPC/SEC data in Empower (Part 3).


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