RT reference and RRT fields in Empower 3 Proc Method

Empower2018

I have a method where only the RRT values of the known impurities are listed, not the retention times. When listing in the processing method, im confused as to where to list the values. Is it only in the RRT field and I leave the RT blank? Or do I put the values in both the RRT and Rel RT Field parts? What about the RT Reference, do I just leave that blank?


I have been outspoken about how some Help articles in Empower 3 are quite confusingly worded and unhelpful but without a doubt the worst example of this has been the RT reference and RRT fields, and the explanations for it. All I wanted was simple examples as to how they worked and after reading the articles on Help several times, I am none the wiser as to what they mean, and there are several different interpretations of it too! If anyone who uses these fields regularly could explain in clearer words, maybe with an example that would be great! 

medicnman

Yes, just select each respective RT Reference peak in the drop down.

DavidHPLC

If you want Empower to show RRT data for peaks (you might be asking for something else):

In the Components table set your main peak (RRT 1.0) under Relative RT Reference and check Default Pk checkbox for that peak (might work without that).

In your Peaks table show RT Ratio column where you will see the RRT for your peaks.

Empower2018

Hi DavidHPLC, yes the default peak will as standard report relative retention times for unknowns. But if I already know the RRT values for the knowns whats the difference between entering these times under the RRT column and leaving the actual RT field blank? Is it better to just leave the RT Reference blank and use the Relative Retention time field as the active peak? There are a lot of options to use between RRT, Relative RT and RT Reference, its a bot confusing. 

medicnman

It sounds like you are attempting to ID peaks based on a known RRT, relative to a reference peak, instead of a RT and RT window. Please indicate if this is the case; I can provide some clarity for your question. Empower handles it elegantly.

medicnman

I have some time, here is the quick and dirty version.

1. Enter your reference peak in the components table, the peak by which all RRTs are based for identification. Enter your reference peak's expected RT.  You can set the RT to anything really, it will be manually changed later.
2. Enter all other peaks in the component table with RT windows, use a simple default of 0.2 or something. Enter all the other peaks RRT values.
3. Set all of these peak's RT Reference to the reference peak name. It should be in the drop down.
4. Open your processing method with data, manually enter or manually drag the Peak ID line to the reference peak, calibrate and quatitate.....
5. Poof!, all of your RRT peaks will be ID'ed if the method is robust. You may need to adjust the RT window. Just do not adjust any RRT peak's RTs manually, it will alter the RRT setting in the PM. Only move the reference peak RT as needed.

You can use this for multiple Reference Peaks, it just becomes a birds nest sometimes.

Empower2018

Thanks very much medicnman, Can you also use two RT references? For example an impurity sample with two APIs so you want all named impuritys of API1 to have their RRT calculated using API1 and the same for API2?

Empower2018

Thanks very much! I was concerned that there would be some issue when using two RT Reference entries. 

DavidHPLC

It works with multiple RT Refs.