Problem trying to see the max pressure in a chromatgram using a custom field.

I want to see the max pressure per chromatogram so I add a pressure channel to my instrument method. I created two CFs to measure the max pressure, I don't want the pressure at a particular retention time as I run a gradient and the max pressure can vary, I want Empower to record the pressure at each retention time from start to end of injection, so my first CF (called Pressure) is Y-Value[Retention Time] then a second Result CF called MAX(Pressure). I add the collected pressure channel to my method set under derived channels and attach a processing method to it.

Problem is, Empower is only giving me values for Pressure for any integrated peaks on the pressure trace instead of every single value on the x axis. I know Retention Time is a peak characteristic so I can see why its only giving values when peaks are integrated but in my trace I could only have 2 "peaks" integrated on the pressure trace whereas on the highest data point nothing is integrated and I don't get that value for MAX(Pressure), only whatever pressure one of the lower peaks reads.

Is there any way to get Empower to record the maximum pressure of your BSM at any point from start to end of injection, not related to peaks just related to the highest pressure spike? Am I missing a channel or feature? Thanks.


  • Late reply, but...If your pressure trace is consistent across injections: consistent enough that you can integrate from T0 to T-end-run-time...all one peak and only one peak.

    Integrate the pressure trace such that the baseline start is at RT=0 (injection start) and baseline end is a RTmax (end of the injection). The pressure trace's integrated "peak" will have a RT = Pmax; it always picks the peak maxima as the RT. Allowing negative peaks will help the integration.
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