Checking The Volume - BRAND Transferpette-8 electronic Operating Manual

Checking the Volume

Depending on use, we recommend inspection of the instrument every 3 to 12 months.
The cycle can, however, be adjusted to individual requirements.
The gravimetric testing of the pipette volume is performed according to the following
steps and is in accordance with DIN EN ISO 8655, Part 6.
1.
Set nominal volume
2.
Condition the pipette
3.
Carry out the test
Calculation (for nominal 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 variation coefficient (CV %): A % and CV % are calculated
according to the formulas for statistical control.
54
See page 40 for procedure.
Condition the pipette before testing by using pipette tips to
aspirate and discharge the test liquid (distilled H
After this, discard the pipette tips.
a) Attach new pipette tips and pre-rinse one time with test liquid.
b) Aspirate liquid and pipette it into the weighing vessel.
Note:
c) Weigh the pipetted quantity with an analytical balance.
Please follow the operating manual instructions from the
balance manufacturer.
d) Calculate the volume, taking the temperature into account.
e) 3-10 pipettings and weighings per channel in three volume
ranges (100 %, 50 %, 10 %) are recommended for statistical
analysis.
Z = Correction factor
Σ x
i
Mean volume V = x · Z
n
0
· 100 s = Z ·
Each individual channel must be
tested separately.
(for example 1.0029 µl/mg at 20 °C, 1013 hPa)
Standard Deviation
Σ (x
– x ) 2
i
n – 1
O) five times.
2
Coefficient of Variation*
100 s
CV% =
V