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Note:
In colorimetric measurements, when it is possible, use the same cuvette both for zeroing and
measurement. If this is not possible, always match the cuvettes.
In turbidimetric measurements, if you are using multiple cuvettes, always match the cuvettes.
CUVETTE HANDLING
The cuvettes should be free of scratches or cracks. Any cuvette with visible scratches should be
discarded. The cuvettes should be periodically washed with acid. After washing, the cuvettes
should be well rinsed multiple times with distilled or deionized water. Allow cuvettes to air-dry
and store them for long periods of time with caps, to avoid dirt entering inside. Always handle
the cuvette by touching only the cap or its top side (over the horizontal line).
Always store the cuvettes in separate boxes or with separators between them to avoid scratches
on the surface.
CUVETTE PREPARATION
Whenever a cuvette is used, it must be clean inside and outside. When it is placed into the
instrument, it must be dry outside, completely free of fingerprints or dirt.
If the cuvette is not indexed, put the cuvette with the factory mark aligned with the sign on the
instrument top.
CUVETTE OILING (TURBIDITY only)
Warning:
For colorimetric measurements the cuvette should be completely free of any trace of oil.
Do not use the oiling procedure for colorimetric measurements.
To hide minor imperfections and scratches, the cuvettes should be oiled outside with the supplied
silicone oil. This is very important, especially for low turbidity samples (< 1 NTU), otherwise
scratches can contribute and alter turbidity readings.
The silicone oil has the same refractive index as the glass and will not alter the turbidity readings.
It is important to apply only a thin layer of silicone oil.
Warning
: Do not apply silicone oil in excess because it may retain dirt or contaminate the cuvette
holder of the instrument, altering the turbidity readings.
It is very important to apply the silicone oil on a clean, dry cuvette. Apply a few drops of oil and wipe
the cuvette thoroughly with a lint-free cloth. Wipe off the excess oil till you obtain a thin, uniform
layer. If the procedure is correctly followed, the cuvette should appear nearly dry with no visible oil.
