With Empower, RT of peaks not identified - WKB114575

ENVIRONMENT

• Empower
• Retention time

ANSWER

RT reference peak was selected. When selecting this function, the expected retention time for all of the other peaks is adjusted.

ADDITIONAL INFORMATION

See the Help guide.

Temporarily adjusting the retention time based on the retention time of another peak

Using the RT Reference field in the Components table, you can temporarily adjust the retention time of a component based on where the RT Reference peak is found in the chromatogram. The software recalculates the window where the component is expected for each chromatogram. If this field contains the name of another component, and if the reference peak is detected within its RT window, the component retention time in the calibration curve is adjusted temporarily in response to the new retention time of the Reference peak.

Tip: If a component has an RT Reference peak assigned to it, but its RT reference peak does not appear inside the specified RT window, the component is listed as Missing in the Results window.

The adjusted retention time of a component is calculated as follows:

RTadjusted = RTcomp in cal curve x (RTref peak found/RTref peak in cal curve)

The value in the RT Reference does not permanently affect the calibration curve. The RT Reference field adjusts the retention time of the component by the ratio of the retention time of the reference peak to where the calibration curve defines where the reference peak should be. The adjusted retention time becomes the time that the software uses to find the component peak in the chromatogram.

Use RT Reference when one or more of these conditions occur:

• Peaks are close together, and are misidentified when the RT windows are increased.
• You can use a small retention time window for component peaks and a larger window for the reference peak.
• Your chromatography is shifting so that some components elute outside their RT window.

Tip: If your application requires a permanent update to the calibration curve, use the Update RT parameter.

You must enter each RT Reference peak as a component in the Components table, assigning it a unique name, a retention time, an RT window, and a peak-match type so that the software can identify it.