Scanning Spectra; Before You Begin - Waters 2489 Operator's Manual

3. If you press Enter:
• All timed and threshold events in the method are cleared.
• All other operating parameters of the method (λ, AUFS, etc.) are
unaffected.
If you press Cancel (Shift 0), the display returns to the Method choice
list.
4. When you return to the absorbance screen by pressing HOME, the
method number icon displays an asterisk.

Scanning spectra

The detector must make two types of scan to produce an absorbance spectrum:
• Zero scan – A reference scan that characterizes the absorbance spectrum
of the solvent in the cuvette or the flow cell.
• Sample scan – An absorbance scan of the analyte in solvent (after
subtracting out the zero scan of the solvent) to provide the actual
spectrum of the sample.
The detector can measure the spectrum of a sample using the cuvette or the
flow cell. See
flow cell and a syringe"
When using the cuvette, if the contents of the flow cell change, you must
Rule:
rerun the zero scan.

Before you begin

Before you run a spectrum scan, you need to specify the following parameters:
λ1 – Starting wavelength. Scanning begins at this wavelength.
•
λ2 – Ending wavelength. Scanning ends at this wavelength.
•
• Pace – Rate of scanning in nm/min. Determines how fast the scan is
output and data is acquired. The scan data is acquired at the highest
possible resolution for the specified pace. When the pace is set to a very
high number, the resolution is reduced, as illustrated in the following
table and figure.
3-44 Preparing the Detector
"Scanning using the cuvette"
on page
on page 3-59
3-62 for scanning procedures.
and "Scanning using a