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Empower peak area is much larger than the peak area for MassLynx - WKB2764

Article number: 2764

SYMPTOMS

  • Customer reports that the integrated peak area for a peak analyzed with Empower is 50-60 times the area for a different UV detector with MassLynx

  • Reported about UV data but also applies to MS data (and most other analog detectors)

ENVIRONMENT

  • MassLynx

  • Empower

  • MS

  • ACQUITY UPLC Tunable UV Detector

  • ACQUITY UPLC PDA Detector

CAUSE

Time units are minutes for MassLynx and seconds for Empower. So Empower data is 60 times the MassLynx value.

FIX or WORKAROUND

Multiply or divide by 60 to adjust the units for peak area to account for the units used in time measurement.

ADDITIONAL INFORMATION

There is no reason why MassLynx and Empower should give exactly the same result for a compound analyzed on two different inlet systems.
There are many instrument factors (e.g., lamp energy, scale factor) to take into account.

MassLynx calculates peak area for an absorbance detector as µAU*minute. (AU = Absorbance Unit)
MassLynx calculates peak area for an MS detector as Ion Counts*minute.

Empower reports peak area as µV*second (with the detector typically set so that 1V=1AU for a UV detector).
This means that a 1-AU peak is equivalent to a peak height of 1,000,000 height counts from a baseline of 0 V.

Information on Empower integration is included in the Empower 3 Data Acquisition and Processing Theory Guide.
On the Waters website, see the User Support Guide USRM10194650, pages 1-4, Data Conversion section.

 

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