Checking The Volume (Calibration) - BRAND Titrette Mode D'emploi

Checking the Volume (Calibration)

Depending on use, we recommend that gravimetric testing of the instrument be carried out every 3-12
months. Set the 10 ml instrument to calibrate to 3 decimal places (page 61). This time frame should be
adjusted to correspond with individual requirements. The complete testing procedure (SOP) can be down-
loaded at www.brand.de. In addition, a function test can also be carried out over shorter time spans, for
example by titration against a standard. For GLP- and ISO-compliant evaluations and documentation, we
recommend the EASYCAL
www.brand.de.
Gravimetric volume testing according to DIN EN ISO 8655-6 (for measurement conditions, see 'Error
Limits', page 45) is performed as follows:
1.
Preparation of the instrument
2.
Check the volume
3.
Calculation
Mean volume
x = Weighing results
i
n = Number of weighings
Mean value x =
Accuracy*
V – V
A% =
V
0
V = Nominal volume
0
* Calculation of accuracy (A %) and coefficient of variation (CV %):
A % and CV % are calculated according to the formulas for statistical control.
46
™ calibration software from BRAND. A demo version can be downloaded from
Clean the burette (see 'Cleaning', page 54), fill it
with distilled H
a) Dispense 5 drops into a separate receptacle and
wipe off the titrating tube tip.
b) Press the CLEAR key to set the display value to
'zero'.
c) 10 dispensed amounts 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 in the
display. Wipe off the titrating tube tip.
e) Weigh the dispensed amount on an analytical bal-
ance. (Please follow the operating manual from
the balance manufacturer.)
f) Calculate the dispensed volume. The Z factor
takes account of the temperature and air buoy-
ancy.
Z = Correction factor
Σ x
Mean volume V = x · Z
i
n
0
· 100
O and then prime it carefully.
2
(for example 1.0029 µl/mg at 20 °C, 1013 hPa)
Standard Deviation
Σ (x
– x )
2
s = Z ·
i
n – 1
Coefficient of Variation*
100 s
CV% =
V