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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.
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Agilent Cary 8454 UV-Visible Spectroscopy System Installation Guide