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. 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, a simple inspection 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
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% = · 100
V
0
V = Nominal volume
0
*) = Calculation of accuracy (A %) and variation coefficient (CV %):
A % and CV % are calculated according to the formulas for statistical control.
46
Clean the burette (see 'Cleaning', page 54), fill it
with dist. H O and then prime it carefully.
2
a) Dispense 5 drops into a separate receptacle and
wipe off the titrating tube tip.
b) P ress the CLEAR key to set the display value to
'zero'.
c) 5-10 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.
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
™
(for example 1.0029 µl/mg at 20 °C, 1013 hPa)
Standard Deviation
Σ (x
– x )
2
s = Z ·
i
n – 1
calibration software from BRAND.
Coefficient of Variation*
CV% =
100 s
V