1 cleaning the probe end, 3 cleaning of internal reflectance reference, Cleaning the probe end – Metrohm NIRS XDS Interactance OptiProbe Analyzer User Manual
Page 33: Cleaning of internal reflectance reference
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5.2.1
Cleaning the Probe End
Following analysis, the probe end should be cleaned to prevent sample carryover, which could affect
analysis. Cleaning depends upon the sample material. Always follow the precautions on the MSDS
when performing cleaning. Normal samples and cleaning methods include:
Sample Type
Cleaning Method
•
Free-flowing crystalline materials,
pellets, fibrous samples
Wipe from probe end with disposable lab wipe.
Wipe probe window with dampened wipe. Rinse
with de-ionized water, and dry thoroughly.
•
Dense powders which tend to clump,
thick slurries
Wipe from probe sampling area with spatula or
wooden tongue depressor. Clean window using a
mild detergent solution, rinse, then dry.
•
Thick, pasty samples with high oil
content
Dig out using spatula or wooden tongue
depressor. Wash cell and window in a strong
detergent to remove all residual sample material.
Rinse and dry.
Pharmaceutical applications may require a “Cleaning validation” which describes each step of the
cleaning process, solvents to be used, and specific verification tests to determine whether cleanliness
levels have been reached. Because a cleaning validation is sample-specific, Metrohm cannot
recommend detailed cleaning methods for such samples.
The OptiProbe is shown here, sampling a liquid
in a beaker. An automatic stirrer is in use.
Note that the fiber optic bundle is gently
curved, not bent or kinked in any way. This
minimizes damage to internal fibers in the
bundle.
5.3
Cleaning of internal reflectance reference
The internal reflectance reference is a small piece of 99% reflectance (nominal) Spectralon™. This
material is quite rugged, non-hygroscopic, and stable with temperature.
In spite of these qualities, the internal reflectance reference can become contaminated. This chiefly
occurs through foreign materials becoming lodged on the end of the OptiProbe, then deposited on
the internal reflectance reference when the probe is placed into the reference position.