Beckman Coulter Multisizer 4, User Manual

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PN A51387A
B
9-1
CHAPTER 9
Troubleshooting
Resolving Common Problems
Reducing Noise
Noise often appears as an increased small particle count or varying particle counts that do not
follow an expected size distribution.
Increasing or varying noise levels can be caused by:
• Electrolyte solution . If you are using a small aperture tube, increasing electrolyte salt
concentration will increase the signal to noise ratio for particle sizes below 1 µm.
• Low aperture current . If you are using a small aperture tube or a concentrated electrolyte
solution, the Multisizer 4 software will automatically select a low current/high gain setting.
• High aperture current . If the aperture current is set too high, the electrolyte solution in the
aperture can heat or boil, causing noise. Reduce the current or increase the conductivity of the
electrolyte solution.
CAUTION
Current set too high can saturate the amplifier, damage the aperture orifice,
distort your results, or damage cells.
• Atmospheric interference . A dust-laden environment, platform vibration, or a loud
environment can increase noise levels.
• Electrical interference . Any form of electrical interference can cause random noise patterns
and pulses. Move the Analyzer to a different power source or a different location.
• A damaged aperture . If noise levels are increasing or varying (particularly on blank runs), the
aperture may be damaged. Install a new aperture tube (page 3-2 ).
Reducing the noise level is particularly important if you are using an aperture tube smaller than
100 µm, or if you are measuring particles near the minimum threshold (2% or 10% of aperture
diameter).
For instructions specific to 20 µm and 30 µm apertures, see Using Small Aperture Tubes (20 µm and
30 µm)
, page 3-4 .