Checking The Volume (Calibration) - BRAND Dispensette TA Operating Manual

Depending on use, we recommend that gravimetric testing of the instrument be carried out every 3-12
months. This time frame should be adjusted to correspond with individual requirements. The complete
testing procedure (SOP) can be downloaded at www.brand.de. In addition, you can also carry out function
checks at shorter intervals, e.g. dispensing the nominal volume into a volumetric test flask (volumetric
flask with 3 marks, DKD calibrated). 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 32) is performed as follows:
1.
Preparation of the instrument
2.
Check the volume
3.
Calculations
Mean volume
x = results of weighings
i
n = number of weighings
Σ x
Mean value x =
n
Accuracy*
V – V
0
A% = · 100
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.

Checking the Volume (Calibration)

™ calibration software from BRAND. A demo version can be downloaded from
Clean the instrument ('Cleaning', page 35), fill it
with distilled H O and then prime it carefully.
2
a) 10 dispensing operations with distilled H
3 Volume ranges (100 %, 50 %, 10 %) are
recommended.
b) For filling pull up the piston gently until the
upper stop of the volume set.
c) For discharge depress piston slowly and
steadily without force until the lower stop.
d) Wipe off the tip of discharge tube.
e) Weigh the dispensed quantity on an analytical
balance. (Please follow the operating manual
of the balance manufacturer.)
f) Calculate the dispensed volume. The Z factor
takes account of the temperature and air
buoyancy.
Z = correction factor
(e. g., 1.0029 µl/mg at 20 °C, 1013 hPa)
Mean volume V = x · Z
i
Standard deviation
s = Z ·
O in
2
Σ (x
– x )
2
i
n – 1
Coefficient of variation*
100 s
CV% =
V
33