How to define Softmax Pro "Range?" result as 0

[Guest Alex]

Dear Mabtech-Team,

I'm Alex, Scientist, working with ELISAs and the Softmax Pro Software.

I have a problem regarding the formulas:

In our table we have one column 'Value', giving the measured ODs. In the next column we have the back calculated concentration using the formula: InterpX(Standard@Standardcurve,Value).

In some cases the Value is lower than the detection limit of the device giving the "Range?" expression in the back calculated concentration column and all other columns. Now my question is, if it is possible to define "Range?" as zero (0). Ideally integrated into the column formula. I tried with the NAN error code MakeErr(106)for the "Range?" expression but without success.

Best,

Alex

[Christian@mabtech.com]

Hi There Alex!

This question is more suitable for the support team at Molecular devices. 

But hey, we can give you our best shot, we also use Softmax at Mabtech:

I am unaware of a way to change so that the "Range?" result can be changed to zero. Molecular devices want to point out that with the current OD value you are off the linear range of the curve where quantification is not reliable. 

But we do have one tip. In Softmax you can add "weighting" to your curve-fit. You then enter a formula: 1/MeanValue^2 in the box for weighting like show below:

This will result in Softmax giving more credence to the lower OD values when doing the curve fit. 

Here is the result without this weighting:

And here is the result after this weighting:

[Guest Alex]

Hi Christian,

 

thanks for the quick reply - appreciate it. I tried it and it works in some cases but not for all. I will contact the support then.

 

Best,

Alex

[Guest Alex]

Follow up solution from Molecular Devices to the problem (for anyone facing the same issues):

1. Creation of a separate column named “Lower Asymptote” with the Formula: ParmA(Standard@StandardCurve). This just gives you the value of the lowest measurable point of the curve. 
2. Creation a second additional table column with the following formula: If (Value<'Lower Asymptote',0,Concentration). This formula displays all Values which are below the lowest measurable value as 0 and everything else as the backcalculated concentration. 

[Christian@mabtech.com]

thanks for the follow up!