Variable Wavelength Detector (Vwd); Cell Test - Agilent Technologies 1220 Infinity II LC User Manual

9
Test Functions and Calibration

Variable Wavelength Detector (VWD)

Variable Wavelength Detector (VWD)

Cell Test

VWD Cell Test Description
The Cell Test compares the intensity of the deuterium lamp measured by the
sample and reference diodes (unfiltered and not logarithmized) when the
grating is in the zero-order position. The resulting intensity ratio
(sample:reference) is a measure of the amount of light absorbed by the flow
cell. The test can be used to check for dirty or contaminated flow cell
windows. When the test is started, the gain is set to -1. To eliminate effects due
to absorbing solvents, the test should be done with water in the flow cell.
The test should not be performed using the micro flow cell, since the reduction in light
N O T E
intensity will cause the test to fail.
Evaluating the VWD Cell Test Results
The intensity ratio is dependent on the degree of contamination of the flow
cell windows, and on the type of flow cell used. The lower the ratio, the more
light is absorbed by the flowcell.
Table 34
Cause
Absorbing solvent or air bubble in flow cell.
Dirty or contaminated flow cell.
162
Probable causes of excessive flowcell absorbance
Corrective action
Ensure the flow cell is filled with water, and
free from air bubbles.
Exchange the flow cell windows.
1220 Infinity II LC System User Manual