General Considerations; Spectrophotometer Design; Making Measurements - Agilent Technologies Cary 8454 Installation Manual

3 Good Measurement Practices

General Considerations

General Considerations
There are many factors that can affect the results of your measurements. This
section provides brief discussions of some of the more important ones.

Spectrophotometer Design

The sample compartment of the spectrophotometer is open. Unlike
conventional instruments, the Agilent Cary 8454 UV-Visible
spectrophotometer does not suffer from ambient false light. The open sample
area is easier to access, and it is easier to connect tubing to a flow cell or
thermostattable cell holder.

Making Measurements

Blank (Reference) and Sample Measurement
Your spectrophotometer is a single beam instrument so you must measure a
blank before you measure a sample. For high accuracy measurements, the
blank and the sample measurement should closely follow each other.
In general, a blank measurement should be repeated as often as is practical.
Even in a thermally stable environment, a blank measurement should be taken
every half hour to ensure accurate results.
Chemically, the only difference between the blank and the sample should be
the presence of the analyte(s). For measurements with liquid samples, the
blank should be a sample cell filled with the solvent you plan to use.
32 Agilent Cary 8454 UV-Visible Spectroscopy System Installation Guide