Custom Fields

Hello--We are presently exporting our Empower 3 data into an excel spreadsheet (for an impurity method with lots of peaks).  What we would like to do is set up a custom field that would point to the blank so that peaks in the blank can be subtracted out of the sample for a corrected area determination.  Is there a way to make a custom field to do that?Deb

Best Answer

  • Accepted Answer

    Hi Deb

    What you need to create is an Intersample custom field calculation. You need to identify you blank injection in the label column of the sample set f.ex. as BL.

    Then create a CF like this : Corrected_Area = Area-(BL..(Area))

    Your blank injection needs to be at the start of the sample set.

    See the attached example for details.

    best regards

    Rune

Answers

  • I would assume this requires the peaks to be "named" in order to match them?

  • Thank you so much!!  (Danke or Dankje!!))

  • Hi Deb

    Kevin is right, it requires naming of the peaks in the component table of the processing method.

    best regards

    Rune

  • Hello Again,

    I was trying that method, but i have a problem.  I am running impurities and i need to have a curve reference and relative responses selected for my known and unknown impurities. When I do that, the table blocks out the Y value where the custom field is added.  Is there another way I can enter the information to correct the areas for the knowns and unknowns that have interference in the blank?

    Thank you

  • Hi Deb

    I would think that Empower would still use the corrected area of the peaks even if they have a reference curve as long as you have selected the corrected area as the basis for calibration for the reference peak. This will apply only to known peaks = peaks present in the component table, so your unknown impurities will not be corrected, since it does not have these named in the component table. I cannot think of a way to do this on the unknown peaks, other than having them named in the component table.

    The other solution would be to do a subtraction of the signal from the blank in all standards and samples but this is a bit dangerous if the retention times are not completely stable.

    best regards

    Rune

  • We have some projects when we had to correct impurity peaks with placebo and/or diluent peaks. We named the peaks and used component type custom field to enter the placebo peak area (the custom filed will be is in the sample set were you adding your standard concentration). It requires some typing but it still easier for us than using Excel and we still can do all the calculation then with Empower, and use the reports. We use these CF more than a year without any issue.

    Best regards,

    Eva

  • You could also do the blank correction in the method set to subtract the entire blank injection from each other injection.  You just make a derived channel where the First channel is your usual channel and for the second channel you select the - operator and subtract the same channel and select the from injection labeled box and inpur the label for your blank.  One issue with this is that the blank injection will look perfectly flat so you may have to process it twice to be able to see what peaks are there, but other than that it will subtract out the blank contribution in all other injections

  • Hi Rune,

    how will the custom field look like, if you had to subtract the average from three injections ?

    thanks

  • Hi Marta

    Maybe this would work:  Area-(BL*.%..AVE(Area)). It would require that you label all 3 blanks as for example BL1, BL2, BL3. It will also require that you insert a "Summarize custom fields" function in your sample set after the blanks.

    Good Luck.

    best regards

    Rune

  • Thanks so much Rune, it works ;-) I just had to change * to a ?
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