How create the custom fields formula ?

I would like to create a custom field to calculate the assay of two API in the same analysis, can someone help me? 
if I write you the formula, can you help me create a formula step by step?


  • Whats the formula? There are several custom field options for assay so I'm sure there is a way to do this.
  • are CF required here ? can assay of 2 APIs not been completed in processing method with dilutions, purity component table ?
  • These are the formula: 1 = (area sample average 2 replicates* weight std * purity std in % * 100)/(area std average 6 replicates * 50000*0,05).

    2= (area sample average 2 replicates* weight std * purity std in % * 100)/(area std average 6 replicates * 20000*0,20).

    How Can i create the custom fields formula?
    The chromatogram is the same for Boh API .
    Can Young help me ?
    Many thanks
  • Can someone help me?
  • You need to use the component editor to enter you standard amounts. You need to use the sample weights and dilutions field within the sample set method to accommodate your standard weight and dilutions.

    Empower will then calculate the concentration of your analytes in the amount field.

    To average the two replicates you can most easily generate an average by using the same sample label in the sample set for replicate one and two. You can then setup a report to group samples by label and give you an average for each group.

    If you want to use the average value for a calculation down stream, then you will need the following custom field:


  • Many thanks,
    But if i have two api in the same analysis and in the same chromatogram, How can i use sample weight and dilution etc.? I ma obliged To ceate A formula in the empower project.

  • First row - Values for API1
    Second row - Values for API2

  • Can you describe me step by step?
  • @egio : What are you getting stuck on exactly?  Can you also describe where the 50,000, 0.05, 20,000 and 0.20 come from in those two formulas?  Are those related to the dilution schemes of the two different APIs, and if so, what is your typical prep (e.g. 20 mg/100 mL, diluted 1 mL in 50 mL)?  Also in your original formula, why the *100 if your purity is already in % (like 99.2% purity value used) that for unit conversion of some sort?
  • egio said:
    Can you describe me step by step?
    In the Processing Method (PM), you enter names and retention times for both APIs. Pull APIs into Component editor in Sample Set Method editor by clicking on the PM button (the left hand of the 2 buttons w/ yellow on them) once you open the Component editor (Amounts button). Both components will show up. Enter concentrations, purity, etc. for each (taking into account their dilutions makes it all a bit simpler). Do the couple of clicks so you can see samples as well. Enter your Label Claim values for each component there. Enter Sample dilutions in the first table. Process and you should be there.
  • Many thanks, I managed to do It. Now i would like To perform the calculation on empower with bracketing .I have the following sequence ;
    6inj. Std 1 (S1)
    2 inj. Sample 1
    2 inj. Sample 2
    2 inj. Std 2 (S2)
    I would like To calculate the samples With the avearage of the standards before S1and after the samples S2 .
    Can you describe step by step ?
    Many thanks 

  • In sample set, add a "Clear Calibration" line before the Std1 line. Label the 6 injections of Std1 as S0101, label the 2 injections of Std2 as S0102. Label the Samples 1 and 2 as U1 U2 U3 and U4. After the std2 line, insert a Clear Calibration, then Calibrate (making sure the label Reference on the Calibrate line is set to S01* then Quantitate with the Label Reference on Quantitate set to U*). In the component editor of your sample set make sure you have the amounts or concentrations entered in the Value tab for all standard components. Save all changes, bring the standard/sample channels into review, open processing method, and for the standard injections press integrate then calibrate, which builds your calibration curve. File>Save as Calibration to save curves. Then for your sample injections press integrate then quantitate and your amounts will appear.

    Or you can batch process a sample set to generate a result set. Right click sample set, process, use specified processing method, select the method, make sure clear calibration is ticked then click ok- your result set will be generated with amounts stored. Make sure to account for any dilution factors or sampleweights for your samples before saving sample set.

  • How come you add Clear Calibration before STD1?
  • If you do not do this, and do not check that box when processing, previous standards used with the processing method will be included in your calibration curve.
  • The confusing thing about clear calibration though is it only kicks in when a sample set is batch processed or a set of injections/channels are batch processed. That's the usual procedure in our company. When you review raw data using a processing method and cycle through the injections, any standards of different strengths will construct a nonsense calibration curve and hence inaccurate amounts. The only way around it that I know of is to first select the standards which are relevant then the associated results (unknowns). Then select Edit < Clear Calibration and repeat the next selection of your standards/samples. 

    Clear Calibration in the sample set as an added line only "kicks in" during live, line by line processing during batch processing. 
  • I am sorry but i have another question on calculation empower with bracketing. 
    In addition to compiling the sample set as you described me, do I also have to enter a precise formula in the custom fields?
    Can i send you an example to Understand if i have Compiled The sample set well?
  • Hi, yes send on an example of what you are looking for so its more clear. Thanks. 
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