Calculate RSD on alternating injections



I want the be able to calculate the RSD of our reference injections, but we need to do it each time with a different injection. I'm out of inspiration to get them grouped together. This is the situation:


1) at the beginning of the sequence, the reference is injected 5 times

2) after 4 sample injections the reference is repeated

3) in total this are 6 reference injections, RSD needs to be calculated on those


So far no problem, but we can build the sequence endlessly with sample injections. So if we have 8 sample injections, another reference injection is made. Then we need to calculate RSD of this reference injection with the 5 injections at the beginning, but without the reference injection made after 4 sample injection.


And so on for more sample injections. I don't know how to group every time the first 5 reference injections, with each other reference injection sepperately.


Thanks in advance,


  • Hello,


    What software are you using CDS 2.x, Chemstation, EZChrom?


    Marty Adams

  • CDS 2.3.

    I added a screen with a sequence example. In this case we need the RSD on referentie 1 of line number 6,7,8,9,10,20 and 6,7,8,9,10,24


    Analists don't have permission to make changes in the injection list. We use sequence templates. Before start of the sequence, analists do have permission to adjust the sequence.

  • Hello,


    You will need some way to differentiate the initial 5 injections of the standard you want to group with your later injections. In this example CCF, I used the sample label field with SSS to isolate those injections. Once you have that a CCF file can be used to calculate that RSD value for each injection of the level 1 standard in your sequence with the initial standards. You can name and label the CC anything you want but the scope is peak or group and the type is double. You only need the first CC in the screenshot the second was just a test. The formula is copied below.




    RelStdDev("Peak_Area",CurrentSequence.AllIdentifiedPeaks.Where(function  x.Injection.Sample.Sample_CalibrationLevel = 1).Where(function  x.Injection.Injection_SampleLabel.ToUpper.Equals("SSS") OR x.Injection.CreationTime = CurrentInjection.CreationTime).Where(function  x.Compound_Name = CurrentPeakOrGroup.Compound_Name))



  • It can be done with a simple table in the report editor. You have to filter it to Cal type injections, then add a summary for the area column… there is no need for CC magic

  • Hello,


    How in a simple table would you repeat it in such a way as to have the initial 5 standards grouped with the current standard injection to obtain an RSD? If I read the initial request correctly he wants the RSD for each single bracketing injection with the just the initial 5 injections of the same standard. I have done this in standard IR in the past but used a custom assembly as the mechanism. You can do this with a series of simple tables but that means you have a fixed or maximum number of bracket standards the report can accommodate. If the requestor wanted the RSD in a table for the current injection and all previous standard injections then I agree that could be done in a single table using an aggregator.



  • Oh... I see. Sorry, for the first time i don't get the situation.  It's little bit more complicated.

  • Hello,


    I'm the analyst trying to calculate the RSD on the control reference in our sequence.


    I created a ccf file and made the link with the processing method used in the result set. Yet, no additional result is seen in the injection results after reprocessing all injections from the result set.



    First: do I have to change something in my injection list? The sample label field is now empty, what do I need to insert here?


    Second: how do I continue? = how do I import the results from this ccf result into the report editor? How do we filter in the injections using the ccf?


    Thanks for your input!



  • Hello,


    You will need to fix the syntax of the CC as it looks like you have an extra 1 at the end. There is a check file button in the CC editor that can be used to check all expressions in the file. In the sample label field,  I used SSS to isolate the initial standard group.


    Marty Adams 

  • Hello,


    Thanks for the update, I've corrected my typo.


    Yet, receive a lot of errors when applying the "check file button". (see attachment)

    Could you tell us what to replace the "x" with?


    And what does the "SSS" in the formula stand for?


    We're all new in the custom calculations part of the software...





  • Kevin,


    Sorry, I missed this in the earlier reply but the editor in the community page removed all the (X) values from the syntax of the CC. Try the syntax below it should work as I just tested it again. In my example, the SSS is the value I placed in the sample label field for the initial block of standards. 



    RelStdDev("Peak_Area",CurrentSequence.AllIdentifiedPeaks.Where(function (x) x.Injection.Sample.Sample_CalibrationLevel = 1).Where(function (x) x.Injection.Injection_SampleLabel.ToUpper.Equals("SSS") OR x.Injection.CreationTime = CurrentInjection.CreationTime).Where(function (x) x.Compound_Name = CurrentPeakOrGroup.Compound_Name))
Was this helpful?