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10 Checking the Volume (Calibration)
10 Checking the Volume (Calibration)
Depending on use, we recommend that gravimetric testing of the instrument be carried out every 3-12
months. For calibration, set the 10 ml instrument to 3 decimal places (page 21). This time frame
should be adjusted to correspond with individual requirements. The complete testing procedure
(SOP) can be downloaded at www.brand.de. You can also carry out a functional test at more frequent
intervals, e.g., by titrating against a standard solution. For GLP- and ISO-compliant evaluations and
documentation, we recommend the EASYCAL™ calibration software from BRAND. A demo version can
be downloaded from www.brand.de.
Gravimetric volume testing according to DIN EN ISO 8655- 6 (for measurement conditions, see Error
limits, p. 65) is performed as follows:
1. Prepare the instrument
Clean the instrument (Cleaning), fill it with distilled Water and then prime it carefully.
2. Check the volume
a.
Dispense 5 drops in a separate vessel and wipe off the titration tube tip.
b.
Press the CLEAR button to set the display value to zero.
c.
At 10 pipetting series and weighings in 3 volume ranges (100 %, 50 %, 10 %) are recommended.
d.
Turn the hand wheels with both hands without stopping until the test volume is shown on the
display. Wipe off the tip of titration tube.
e.
Weigh the pipetted amount with an analysis scale. (Please refer to the user manual of the scale
manufacturer.)
f.
Calculate the dispensed volume. The Z factor takes account of the temperature and air buoy-
ancy.
Calculation (for nominal volume)
x
= Weighing results
i
Z = Correction factor (e.g. 1.0029 µl/mg at 20 °C, 1013 hPa)
Mean value:
Variation coefficient*:
100 s
CV% =
V
*) = Calculation for accuracy (A%) coefficient of variation (CV%): A% and CV% are calculated using the
formulas of statistical quality control.
Test Instructions (SOPs) are available for download from
66
Operating manual
N = Number of weighings
Mean volume:
Standard deviation*:
NOTICE
www.brand.de
V
= Nominal volume
0
Accuracy*:
V
–
V
0
A% =
* 100
V
0
.
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