Chromatography Forum

Hello All,

I have another question about EZChrom software. Does anybody know how the S/N ratio is calculated during postprocessing. As I know S/N is calculated as height of the peak of interest divided by noise calculated in the reange between the peaks. But it seem to be crazy ? Don't you?

JaroCzajka

you should go to the help in the software and look at the equations displayed there for the noise and S/N calculations.
they actually do comply.
one draw back is that in ezchrom you cannot calculate S/N if you have a peak elution during a gradient stage because the drift of the baseline in many case due to the changing solvent constitution will add a great margin of error.

It seems to me the best way is to do some more "scripting" .
In my opinion I had to store blank chromatogram (base line) and use it as a referance for calculation noise according to the pharmacopea.

you should go to the help in the software and look at the equations displayed there for the noise and S/N calculations.
they actually do comply.
one draw back is that in ezchrom you cannot calculate S/N if you have a peak elution during a gradient stage because the drift of the baseline in many case due to the changing solvent constitution will add a great margin of error.

There are several noise calculation procedures. In Europe one that is applied often requires the noise form a blank run to be applied to the peak heights of the sample.

This specific one can only be calculated in EZChrom with a scripting calculation (custom parameter) where the parameter will store the noise value of the blank run in a temporary file and uses that value for all subsequent sample runs.

JW