Important Hints For Using - Knauer K-7400 Benutzerhandbuch

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Important Hints for Using

> ERROR <
FREEZE
Do not remove the measurement vessel from the adapter before the
sample is molten. Otherwise the danger of damaging the measuring
head is given.
The sample melting can be accelerated by warming up with the
fingers.
1. To ensure a fixed sample volume, always introduce the solutions with
a clean and dry pipette tip into the measuring vessel.
2. Handle the thermistor always very carefully. All abrasive materials
should be kept away from it. Measuring vessel and thermistor should
be cleaned occasionally with KNAUER cleaning solution supplied with
the instrument.
3. (Dilution: 1:10 solution in distilled water of 40±5 °C)
4. A dirty thermistor does not give accurate measurement results!
5. Cleaning and drying the measuring vessels with alcohol or acetone is
not recommended because remaining solvent vapours could cause
false results!
6. Solutions containing proteins, such as sera, can only be measured
once. Freezing causes denaturisation of the protein so that repetition
of the measurement with the same sample would result in increased
values. Thus, in the case of sera, only one measurement is possible
for one sample.
7. Please note the difference between deal and real osmolality. Only real
osmolality can be measured. It is not possible to prepare other
standard solutions by dilution of a calibration solution since the activity
coefficient of the solution changes with dilution.
8. It is sometimes difficult to cool distilled water which is kept in
polyethylene bottles for a longer period. We recommend in this case
storing the water which is used for the zero point calibration in glass
bottles.
9. If the same salt solution is measured several times, it must be mixed
after thawing (stir briefly). During the thawing process ice floats to the
top of the solution. As ice does not contain salt, the top layer of the
solution is diluted while thawing.
10. Calibration solutions can become more concentrated if the bottle is
opened more than 1 our. We recommend using KNAUER calibration
solutions in glass ampoules (Order No. Y240, Y1241, Y1248, Y1250)
11. Depending on the room conditions it may possible that after a longer
period in the standby mode a little bit water is condensed in the
cooling compartment. Prior to the next measuring it should be
removed with a dry cloth.
Using the Osmometer K-7400