Thermo Scientific FINNPIPETTE COLOR Guide D'utilisation page 10

ENGLISH
Evaporation loss can be significant with
low volumes. To determine mass loss,
dispense water to the weighing vessel,
note the reading and start a stopwatch.
See how much the reading decreases
during 30 seconds (e.g. 6 mg = 0.2 mg/
s). Compare this to the pipetting time
from tareing to reading. Typically
pipetting time might be 10 seconds and
the mass loss is 2 mg (10s x 0.2mg/s) in
this example. If an evaporation trap or
lid on the vessel is used the correction
of evaporation is usually unnecessary.
The factor Z is for converting the
weight of the water to volume at test
temperature and pressure. A typical
value is 1.0032 µl/mg at 22°C and 95 kPa.
See the conversion table on page 39.
Inaccuracy (systematic error)
Inaccuracy is the difference between
the dispensed volume and the selected
volume of a pipette.
A = V - V
Inaccuracy can be expressed as a
relative value:
A% = 100% x A / V
Imprecision (random error)
Imprecision refers to the repeatability of
the pipettings. It is expressed as
standard deviation (s) or coefficient of
variation (cv)
n
S
S
=
i=1
s = standard deviation
v = mean volume
n = number of measurements
cv is the relative value of standard
deviation.
cv = 100% x s / v
CAUTION!
The Finnpipette is designed to allow easy
in-lab service. If you would prefer to have
us or your local representative service
your pipette, please make sure that the
pipette has been decontaminated before
you send it to us.
Please note that the postal authorities in
your country may prohibit or restrict the
shipment of contaminated material by mail.
A = inaccuracy
0
V = mean volume
V = nominal volume
0
( V V
-
i
n 1
-
0
)
2
-10-