Agilent Technologies Cary 8454 Operator's Manual page 63

Good Measurement Practices 4
General Considerations
Blank measurement shows a flat baseline (Figure 9 and Figure 10 on
page 64 show a good and a poor baseline)
Cell orientation of blank and sample measurements is the same
Ideally the cell is not removed between the measurements, which means the
cell is filled/rinsed using a pipette or a flow cell is used
Time between blank and sample measurement should be short
Figure 9 Example of a blank on water showing a good baseline
Agilent Cary 8454 UV-Visible Spectroscopy System Operator's Manual 63