Checking The Volume (Calibration) - BRAND seripettor FEP 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.
Gravimetric volume testing according to DIN EN ISO 8655-6 (for measurement conditions,
see 'Error Limits', page 38) 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
i
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)

Clean the instrument (Cleaning, page 40), 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 discharge depress piston slowly and
steadily without force until the lower stop.
c) Wipe off the tip of discharge tube.
d) Weigh the dispensed quantity on an analytical
balance. (Please follow the operating manual
of the balance manufacturer.)
e) 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
Standard deviation
s = Z ·
O in
2
Σ (x
– x )
2
i
n – 1
Coefficient of variation*
100 s
CV% =
V
39