Gilson PIPETMAN 8X200 Manuel page 22

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PIPETMAN 8X200
GRAVIMETRIC TEST
This test is based on the determination of the
weight of water samples delivered by the pipette.
For this test a balance with a sensitivity of 10
is needed.
The recommended operating temperature is
21.5° ± 1.5°C, deionized water stabilized at the
ambient temperature should be used.
To control evaporation, a small amount of water
is placed in the covered weighing vessel.
1) Record ambient and water temperatures.
2) Fit a tip to channel 1 (extreme left) and set the
desired volume by adjusting the volumeter.
3) Pre-rinse the tip once. This measurement will
not be taken into account for the calculations.
4) Cover the receptacle and place it on the
balance pan. Reset the electronic balance, or
record the value (for a mechanical balance).
While waiting for the stabilization, aspirate the
sample using the forward mode.
5) Open the balance door, retrieve the weighing
receptacle, deliver the sample, place the
receptacle on the balance pan and close the
balance door.
6) Allow the display to stabilize, record the value.
7) Repeat steps 1 to 6 as many times as required
by the test (see Chapter
8) Record the ambient and water temperatures
again. Check that the values are still within
the recommended limits.
9) Convert the results from mg to µl using the
correction factor Z*. Use the average of the
first and second values as the test tempera-
ture to determine the correction factor Z.
(For an average temperature of 21.5°C and
atmospheric pressure around 1013 hPa, Z
factor = 1.0032). Calculate the inaccuracy
and imprecision and compare them with the
specifications given in the introduction of the
manual.
19
-5
g
6, Test Frequency).