Scanning with the VWD

NOTE

Access to the scan feature is only possible during run with stopped flow. The spectrum is taken during a stop-flow condition only while the peak is kept in the flow cell.

Set up a run.
Start a run.

While running on the baseline, take a Blank Scan. A background scan is stored in the memory.

**Table:** Blank scan
	Step 1: Blank Scan: scan of the background (solvent) is stored in the memory. Step 2: Sample Scan: scan of the peak of interest is taken while the peak stays in the flow cell (stop-flow condition). Online Spectrum: Sample Scan minus Blank Scan. Here the functions are inactive (grayed out). Will be active in run mode.

When the peak of interest enters the flow cell, stop the flow (set flow rate to zero or open the purge valve) and wait a few moments to stabilize the concentration.

NOTE
Turning off the pump would stop the run and no access to the sample scan is possible.
Open the Online Spectra window ( View > Online Spectra > VWD ) and change the absorbance and wavelength range according your needs.

Figure: Online Spectra Window
Select Sample Scan. A sample scan is taken in the range defined under Miscellaneous in Method Parameter Settings and displays the result (Sample Scan minus Blank Scan).

21-Jun-2025