Empower Tip: Peak Ratios

Tip #306: How to Use the Peak Ratio Functionality in the Processing Method

In this tip for Empower Chromatography Data System (CDS), we will learn how to use the Peak Ratio functionality in the Processing Method.

Peak ratios are sometimes used to confirm the identity of a compound in a sample. The theory is that the ratio of a peak’s area or height between two channels is a constant for a standard. If the ratio is similar in an unknown sample, then one can conclude that the compound is present in the sample in question. This can be calculated using any detection mode, in this case, our example will be with QDa data.

STEP 1

Start by going to the Peak Ratios (MS Ion Ratios) tab in the Processing Method and follow these steps.

1.1 In the Primary Peak Table, select the Component name from the drop-down list.

1.2 Enter a Primary Peak Identifier.

1.3 Select the Primary Channel Description from the drop-down list.

1.4 Select the Primary Channel Name from the drop-down list.

1.5 Select Area or Height for Peak Response.

1.6 Highlight the row by clicking on the row number and the Secondary Peak Table becomes available.

1.7 Enter a Secondary Peak Identifier.

1.8 Select a Secondary Channel Description and a Secondary Channel Name from their respective drop-down lists.

1.9 Optionally you can enter a Peak Ratio Tolerance %. Empower compares the ratio in the unknown sample to the ratio in the standard. If the ratio is outside of the tolerance % then the ratio in the unknown sample will be flagged. The standard needs to be identified as a reference as described in step 3 below for this to work.

STEP 2

Populate the channel table within the Method Set with the 2 channels you are working with.

STEP 3

Check the Peak Ratio Reference box for the standard (in this case it’s a system suitability sample) in the Sample Set Method or Alter Sample if the data has already been collected. (Notice: The Peak Ratio Reference field is hidden by default.)