Flagging off-scale data as invalid

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Shawn Dilley
Posts: 3
Joined: Wed Jul 02, 2014 9:52 am

Flagging off-scale data as invalid

Post by Shawn Dilley »

Would it be possible in a future upgrade of Clarity to have the system acknowledge when peaks go off the top end of scale (flat top) and consequently flag the data in an unmissable way as being invalid.

This would be specifically when obtaining relative % area results (normalisation calc) and you would also need to be able to flag certain peaks to not be included/counted (primarily speaking this would be a solvent peak for example).

Reason is that we generally view our data on screen and in printed form at about -10 to 200mV (FS is 1000mV) so unless you check the height column carefully it is easy to miss that a peak is actually off scale.
Shawn Dilley

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Daniel Mentlik
DataApex Support
DataApex Support
Posts: 350
Joined: Fri Mar 27, 2009 3:15 pm

Re: Flagging off-scale data as invalid

Post by Daniel Mentlik »

Hi Shawn,
Clarity already has several means of getting a warning of overloaded peaks, have you considered using any of it?
1) You can set up addition of an event to the chromatogram graph when signal overload happens. This would create vertical line in a moment where the overload happens, in case you only limit the y-axis and not the x-axis range you would see the event in the graph as a visual notification. The event can be created using Even Table.
2) You can display Preview Graph in the Chromatogram window. Unlike the main chromatogram graph view, the preview is always full-scale display, thus cut-off peak would be visible even when you work with fixed range.
3) You can use SST Extension to evaluate the cut-off peak and add a marking to the report whether the evaluation is OK or not. In case of the SST Extension, you would need to make sure your baseline is on consistent level as SST Extension does not have access to the absolute signal level data, but only to reported Peak Heights which it can evaluate.
4) You can use a user column to add a notification into the Result Table whether the signal is cut-off or not. This notification can only be numerical (no texts) but can warn about cut-off peaks too.

Please let me know if you want to hear more about particular settings.

Unfortunately deciding automatically on the cut-off is somewhat difficult, as each detector behaves differently and has different cut-off levels. Clarity does not know and does not need to know the range of the detectors so it does not have an opportunity to react on its own, need to cooperate somehow with the control module. Changes would have to be done on several places (control modules, SDK, Clarity) and I do not currently have a clear view how to do this consistently across different detectors. If you have any design suggestion, please let us know to support@dataapex.com .

Best Regards,
Daniel Mentlí­k

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