Level specific dilution factors in the compound table of the calibration [OpenLab 2.5]

Question

Hello, Is there a possibility in OpenLab 2.5 to add level specific dilution factors in the compound table of the calibration? Is there possibly an approach via a Custom Calculation? In detail, it is a multi point calibration with three calibration levels. For each substance, there are three stock solutions with weights of the same quantity per level. For the preparation of the following working standards, substance-specific dilution factors are specified, resulting in three multi-substance solutions in the concentrations 50%, 75% and 100%. In addition, we use the bracketing mode of the Injection List, which could make our project even more complicated. 
 Thank you and best regards, coh

martin.adams · Accepted Answer

Hello, 
 
 From your calculation it looks like the weighting terms are missing. Those terms in that calculation replace the N term in the more standard least squares regression equations when no weighting is done. Below I did the calculation for some test data in excel with the Agilent calculation and a standard non weighted equation and got the same results for all. I have the weight included but all set to 1 for a non weighted regression. If you are not weighting the levels you could use the standard calculation shown below with the simple N value in your case 3. 
 
 Marty Adams

X^2 *wt 
 y*wt 
 x*y*wt 
 x*wt 
 wt 
 x^2*wt

25 
 2.65963 
 13.29815 
 5 
 1 
 25

2500 
 24.59538 
 1229.769 
 50 
 1 
 2500

250000 
 263.3264 
 131663.21 
 500 
 1 
 250000

252525 
 290.5814 
 132906.2772 
 555 
 3 
 252525

Agilent 
 upper 
 lower 
 final 
 
 Standard 
 upper 
 lower 
 final

b 
 -383908 
 449550 
 -0.85398 
 
 b 
 -383908 
 449550 
 -0.85398

a 
 237446.1 
 449550 
 0.528186 
 
 a 
 237446.1 
 449550 
 0.528186

b 
 (&Sigma;Y)(&Sigma;X2) &ndash; (&Sigma;X)(&Sigma;XY)] / [n(&Sigma;X2) &ndash; (&Sigma;X)2]

a 
 [n(&Sigma;XY) &ndash; (&Sigma;X)(&Sigma;Y)] / [n(&Sigma;X2) &ndash; (&Sigma;X)2]

Level specific dilution factors in the compound table of the calibration [OpenLab 2.5]

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