Empower 3 standard addition calc.

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6 posts Page 1 of 1
I have been attempting to make a custom field for the usp <467> residual solvents calculation.

Standard component concentration*sample component area/(sample weight*(standard component area-sample component area))

This is a straight forward calc but when dealing with multiple solvents I'm running into issues because each component is added individually to the a portion of the sample solution so I'm comparing multiple standard to one sample, and if the sample has more than one solvent it's going to calculate the one I'm not considering with that standard. I would love to be able to perform this calc as a calibrate/quantitate function in the sample set, but it won't work with the way empower does "calibrate" even changing the x/y variables in the processing method (unless I'm missing something, some magical property of empower that's evaded me).
I've gone through several iterations of this calc in my attempts, but those that have experienced empower software know it's not the most user friendly thing and is beyond vague in its help topics.

My next attempt will be trying to use the standard amounts to cancel out sample matrix peaks in the standard:

ResSolv = (S%..(CCompRef1[Amount])*CCompRef1[Area])/(Sample weight*(S%..(CCompRef1[Area])-CCompRef1[Area]))

Plugging 0 into the standard amount for components that aren't in the respective standard. Not sure exactly how empower will treat this, if it will complete the calc and if it does how it will report the result, average, highest value or what.

Any input would be greatly appreciated, if you have a single point standard addition calc that works with multiple components and samples and your willing to share that would be awesome.
I don't understand what you are trying to calculate here, maybe can you give an example of what you have in the component editor and a list of results.

You are making the calculation much harder than it needs to be with that custom field though. Based on the formula you outlined you just need to create a custom field: Amount-CCompRef1[Area] and that will do the same job as your big long formula. Amount is (Sample Area*Value in Comp Editor* Dilution/Standard(s) Area * Sampleweight) which is most of your formula then subtract the CCompRef1[Area].
In the component editor everything is unchanged, there are ~33 USP reference solvents used for system suitability and peak id of class 1 and 2 solvents, these are not calculated though. There are numerous other solvents that can be tested for and it depends on what was used during the manufacturing process these are class 3 and are calculated using my calc above. I have the calculated solvents selected in CCompRef1 and the concentration in the amounts, 0 for those that aren't present in the standard.

What we're trying to accomplish is subtracting out sample matrix from the standard to get the actual standard area in the presence of sample, then determine the concentration of the solvent in the sample in ppm.

Amount-CCompRef1[Area] isn't the same thing

It would have to be Amount*Standard area/(standard area-sample area)
Amount*(S%..(CCompRef1[Area])/(S%..(CCompRef1[Area])-CCompRef1 Area]))

Will the Calibrate/Quantitate functions allow me to perform the subtraction with only a designated standard?
How will empower treat the sample that contains acetone and ethanol that is being calculated against a standard for acetone this is my dilemma, I need to be able to select what the standard is being used for in the case where a sample is littered with other solvents. This is why I was asking about the "summarize custom fields incrementally" and the use of a sample text field in an earlier post.

My solution for this was to use the standard amount (S%.. CCompRef1[amount]) to cancel the peaks that aren't being used to calculate with that standard.

If it helps our typical sample set sequence is:
Class 1
Class 2A
Class 2B
#Class 1 system
#sample (U*)
#!standard spiked sample (S*)
! standard ID soln

#= Repeated per sample
!= Repeated per solvent standard

There is a lot to empower and I'm learning as I go with this since no one at my job has taken the time to do a deep dive into the inner workings of the program, so I appreciate the input.
I just thought of doing a Boolean custom field with a sample text field for the standard

Sample text field= Solvent name


EQI(solvent name, CCompRef1)*Amount*(S%..(CCompRef1[Area])/(S%..(CCompRef1[Area]-CCompRef1 [area]))

If EQI works like that.

This may have solve a 20 year old residual solvents riddle
Thanks for the extra information. Did you try the Boolean suggestion I made in your first thread? Did that do anything for you?
The Summarize Custom Fields only works if you have a summary function like AVE or MAX in your formula so its not relevant here.
You could try your Boolean suggestion and see if that works, but you need the extra [Name] in it ie EQ(Solvent_Name, CCompRef1[Name])* etc. Im not sure if that would work becasue you are asking Empower to compare two different data types (ie Text and Peak) but its worth a try. If it helps too you can always set up an extra custom field within the component tab (Component, Real, custom field) and populate that if you needed an extra paramater in your formula eg EQ(Component_Field,100)*...etc.
I didn't try that suggestion, it was too restricting for what I was looking for, I did appreciate the input though, but I think we're closer now.
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