Agilent Technologies 8453 Operator's Manual page 191

Table 43
Diagnostics and Troubleshooting
General Troubleshooting Hints
Measurement Results Indicate Excessive Noise in Part of the
Spectrum
The selftest (only Agilent ChemStation software), lamp intensity, and
stability diagnostics within the software can aid in diagnosing problems
within the optical system which contribute to excessive noise. Low intensity
in one wavelength range may not preclude you from using the
spectrophotometer at another wavelength range where the intensity is
acceptable. Causes and solutions for excessive noise in part of the spectrum
are shown in Table 43.
Excessive Noise in Part of Spectrum
Possible Causes
One of the lamps may be turned off when
making measurements. Measurements taken
with the deuterium lamp off exhibits
excessive noise in the UV wavelength range.
Measurements taken with the tungsten lamp
off exhibits excessive noise in the visible
wavelength range.
Noise in the UV wavelength range may be
caused by a weak or defective deuterium
lamp.
Flow cells and cuvettes, which reduce and/or
distort the colimated light beam used in the
spectrophotometer, can result in low lamp
intensity at the spectrograph.
Solvent or buffer blocks light in a certain
wavelength range.
Fingerprints on cuvettes or flow cells typically
absorb light in the UV range of the spectrum.
Source lens or spectrograph lenses dirty or
fogged.
Spectrophotometer lamp supply (SLS) board
may be defective.
Action
Switch on proper lamp.
Exchange the lamp. Lifetime of the deuterium
lamp may be influenced by the number of
ignitions.
Change cell to standard type. Glass absorbs
in the low UV region and causes high noise.
Make sure that your flow cells and cuvettes
are made from quartz.
If information is required in such a
wavelength range, a solvent or buffer that is
transparent in that range should be used.
Clean your flow cells or cuvettes with a lens
cleaning tissue.
Clean lenses.
Exchange SLS board.
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