Peak Ratios - wkb249484

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Article number: 249484

OBJECTIVE or GOAL

Use the Peak Ratio functionality in the processing method.

ENVIRONMENT

Empower
Tip of the Week #306

PROCEDURE

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 is with QDa data.

STEP 1
Start by going to the Peak Ratios (MS Ion Ratios) tab in the Processing Method and follow these steps (Figure 1).

In the Primary Peak Table, select the Component name from the drop-down list.
Specify a Primary Peak Identifier.
Select the Primary Channel Description from the drop-down list.
Select the Primary Channel Name from the drop-down list.
Select Area or Height for Peak Response.
Highlight the row by clicking on the row number and the Secondary Peak Table becomes available.
Specify a Secondary Peak Identifier.
Select a Secondary Channel Description and a Secondary Channel Name from their respective drop-down lists.
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 %, the ratio in the unknown sample will be flagged. The standard needs to be identified as a reference, as described in step 3, for this to work.

STEP 2
Populate the channel table within the Method Set with the two channels you are working with (Figure 2).

STEP 3
Select the Peak Ratio Reference box for the standard (in this case, it’s a system suitability sample) in the Sample Set Method, or in Alter Sample if the data has already been collected (Figure 3). (Notice: The Peak Ratio Reference field is hidden by default.)

STEP 4
Process the Sample Set and observe that the ratio is 72.302 in the system suitability sample (Figure 4).

STEP 5
The ratio is 60.571 in the sample (in this case, it’s a bracket standard), which is outside of the tolerance and is flagged as a faulted result (Figure 5).

ADDITIONAL INFORMATION

You can do multiple ratios for multiple components.
This can be done with either the Pro or QuickStart interface.