Empower 3 calibration curve equation coefficients in CFs

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8 posts Page 1 of 1
So when Empower 3 makes a calibration curve (first order linear in my case) it also makes an equation, that it can display on report methods under calibration plot. As i understand it, in Emp3 this equation is expressed as y=B*x+A, where B and A are Polynomial Coefficients.

The question is, how do i extract those A and B values into a custom field for other calculations? B and A are fields on their own, so i tried to make a custom field that simply equals B, but it returns bizzare values, different for each injection of my calibration.

If i open my calibration in Review, go to Results window, i can see the A and B values in Peak Calibration Curve table, but how do i get them to a custom field?
I made a peak, real custom field and had just B as the formula and it worked fine for me for each injection- I got the B value of the calibration curve used to quantify that sample. Are you sure you had the sample type and peak type set to all? I had a search order of result set first, but this shouldn't make a huge difference as such. and my order was Linear thru zero, so that's the only difference I can see between mine and yours.

what do you need the B value for- are you multiplying it against a constant?
EmpowersBane wrote:
I made a peak, real custom field and had just B as the formula and it worked fine for me for each injection- I got the B value of the calibration curve used to quantify that sample. Are you sure you had the sample type and peak type set to all? I had a search order of result set first, but this shouldn't make a huge difference as such. and my order was Linear thru zero, so that's the only difference I can see between mine and yours.

what do you need the B value for- are you multiplying it against a constant?


In my case there are no samples, the only injections are the standards making up the calibration curve. We use the calibration equation to check linearity and deviation of injector volumes. What i need to calculate in the end is to solve x when y=0.

I believe that for sample injections it would return the correct A and B values, but i need them in a custom field starting from the first injection of the calibration curve.

Perhaps there is another way to calculate x when y=0, an intercept, i suppose?
Yes, I tried a few different fit types like linear, third order, quadratic etc but I still get the correct A and B values returned for the 2 CFs where the equation is just A/B. I'm not sure what else could help. Maybe someone here will know more..
Hi,

I will use this thread because i have a similar problem

I am creating a costum field also for the linearity parameter such as cdsman1001 and i also need to make a calculation with the calibration curve values (A and B).

Fortunately I can get the correct values A and B, but I am having problems with the results generated from them:

What I intend to do is create a field to generate a Corrected Response (I know that the empower already has that field, but it doesn't give me a result) ,i.e. pass a concentration through the calibration curve to give me a response.

Note: This is just a calibration curve, no samples.

The field i tried was:

(Amount * B) + A

What I wanted to see would be:

Amount---Area-----------B----------A------Corrected Response
0.1247-----13117-----95041---- -790------12642
0.1996---- 20397-----95041---- -790------19760
0.3992---- 38268-----95041---- -790------38730
0.7984---- 74786-----95041---- -790------76671
1.996------193154----95041---- -790------190492
2.9939---- 283436----95041---- -790------285333
3.9919---- 380647----95041---- -790------380184


What I see is:

Amount---Area-----------B----------A------Corrected Response
0.1247-----13117-----95041---- -790------13117
0.1996---- 20397-----95041---- -790------20397
0.3992---- 38268-----95041---- -790------38339
0.7984---- 74786-----95041---- -790------74781
1.996------193154----95041---- -790------192313
2.9939---- 283436----95041---- -790------284869
3.9919---- 380647----95041---- -790------380181

Seems that my values are getting closer and closer to the values i want as i go through the calibration points.

What I believe is that the values of A and B are being calculated at the same time as my field, and therefore only the last result is true.

How can I define that a costum field is only calculated AFTER the calibration is complete.

Calibration first and then Custom Field with values A and B


Thanks
There is a theory that custom field names have an effect on the order of calculation and that alphabetical order is priority. You could split up the calculation. So make a peak, real, calculated cf called Corrected_Amount and the formula is Amount*B. That way Amount and B have values so that Corrected_Amount will generate a value and the letters are in order.
Then create a second CF called Corrected_Final with a formula Corrected_Amount+A. And critically, before you review your standard injections, clear any previous calibrations which may be distorting amounts and number of points on the curve. Try changing the search order to result set only and again, make sure to clear calibration before processing a sample set to generate a result set.
Another tip is to create a Result,Real cf which will only generate one result per standard/chromatogram. Set the formula as MAX(Component Name(B)+Component Name(A)) and it should be square brackets around the B and A.My phone hasnt got the option! You must name the component exactly as it is in the processing method and the MAX is essential when referencing a peak name in a Result CF. Essentially there will only be 1 answer per standard so the MAX answer will be the same. This should give you the correct value for Amount*B +A.
Thank you for your answer

The fields are all in Result Set Only, so you shouldn't be affected by previous processing.

I found a way for the result to be correct, but it forces me to do the processing 2 times.

I do "Only Calibrate" first and then I do "Only Quantitate", the first batch is wrong and the second is correct.

It's a work around, I wanted to try to do it in a single processing

I will test splitting the field calculations as suggested ..

Thanks again
Hi
Edit the custom field. Check the *All or nothing* check box.
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