Hach-Lange LICO 690 Basic User Manual - Manual (Page 54)

English 54
A dry thermostat is available for the round disposable glass cuvettes
with 11 mm. The dry thermostat heats up the cuvette to any temperature
between ambient temperature and 150 °C (302 °F).
• Always hold the cuvette/sample cell close to the top to make sure
that there are no fingerprints in the measurement zone of the
cuvette/sample cell. Use suitable transfer pipettes to introduce
samples into the cuvettes/sample cells.
• Slowly add samples to the cuvettes/sample cells to make sure air
bubbles do not form on the cuvette/sample cell wall and in the
sample. Air bubbles will cause false readings.
• If air bubbles are entrapped, remove them by heat, vacuum,
ultrasonic treatment or other suitable means.
• Clean the outside of the cuvettes/sample cells thoroughly before
inserting them in the cell compartment.
Color measurement
Proper sample preparation is extremely important for accurate color
measurement. To make sure that an exact measurement is taken, refer
to the following sample preparation guidelines:
•
Always clean the glass cuvettes/sample cells immediately after use.
• Only use optically preferred samples for measurement. Make sure
the cuvettes/sample cells are clean and show no signs of
opaqueness.
• Slowly add the liquid to the cuvette in order to prevent the formation
of air bubbles in the sample.
The color measurement mode is used to determine absolute color
values in the Hazen, Gardner, CIE L*a*b* or European Pharmacopoeia
color scales.
For each cuvette type (11 mm round cuvette and 10 and 50 mm square
cuvettes), an independent calibration data record is used.
It is possible to calibrate the instrument with one, two or three types of
cuvettes/sample cells and to use these different cuvette/sample cell
types in parallel.
N O T I C E
The samples must be clear and free of turbidity. If products in paste or solid form
cannot be measured directly, the product must be melted before being transferred
to the cuvettes/sample cells. Make sure the cuvettes/sample cells do not contain
any air bubbles.
N O T I C E
Before using disposable cuvettes/sample cells made of PS (Polystyrene) or
PMMA (Polymethyl methacrylate), be sure that the cuvettes/sample cells will not
be destroyed by samples, otherwise the cell compartment can be damaged.