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Test liquid: Water, distilled or deionized, "grade 3" water conforming ISO 3696. Tests
are done in a draft-free room at a constant (±0.5°C) temperature of water, pipette and
air between 15°C to 30°C. The relative humidity must be above 55%. Especially with
volumes under 50µl the air humidity should be as high as possible to reduce the effect
of evaporation loss.Special accessories, such as the evaporation trap, are recommended.
CHECKING THE CALIBRATION
The pipette is checked with the maximum volume (nominal volume) and with the
minimum volume or 10% of maximum volume, whichever is higher. E.g. Finnpipette
0.5-10 µl is tested at 10 µl and 1 µl. A new tip is first pre-wetted 3-5 times and a
series of ten pipettings are done with both volumes. A pipette is always adjusted for
delivery (Ex) of the selected volume. Measuring volumes taken from balance is not
allowed. If the calculated results are in the limits, the calibration of the pipette is correct.
Procedure:
1. Do 10 pipettings with the minimum volume.
2. Do 10 pipettings with the maximum volume.
3. Calculate the accuracy (A) and precision (cv) of both series.
4. Compare the results to the limits in the Table 1.
If the results are in the limits of Table 1, then the calibration of the pipette is correct.
Otherwise the pipette must be adjusted and checked again.
Range
Volume
µl
0,2-2 µl
2
0.2
0,5-10 µl
10
1
0,5-10 µl
10
1
2-20 µl
20
2
5-50 µl
50
5
10-100 µl
100
10
20-200 µl
200
20
200-1000 µl 1000
200
100-1000 µl 1000
100
1-5 ml
5000
1000
2-10 ml
10000 ±50.0
2000
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. 6mg = 0.2mg/s).
Accuracy
Precision
µl
%
s.d. µl cv%
±0.050 ±2.5
0.040 2.0
±0.024 ±12.0 0.020 10.0
±0.100 ±1.0
0.050 0.5
±0.025 ±2.5
0.020 2.0
±0.100 ±1.0
0.080 0.8
±0.035 ±3.5
0.030 3.0
±0.200 ±1.0
0.080 0.4
±0.060 ±3.0
0.030 1.5
±0.30
±0.6
0.15
±0.15
±3.0
0.13
±0.80
±0.8
0.20
±0.30
±3.0
0.10
±1.20
±0.6
0.40
±0.36
±1.8
0.14
±6.00
±0.6
2.00
±1.80
±0.9
0.60
±6.00
±0.6
2.00
±1.00
±1.0
0.60
±25.0
±0.5
10.0
±8.0
±0.8
3.0
±0.5
20.0
±20.0
±1.0
6.0
ADJUSTMENT
Adjustment is done with the service tool.
1. Place the service tool into the
openings of the calibration nut at
the top of the handle.
2. Turn the service tool clockwise to
increase, or counterclockwise to
decrease the volume.
3. After adjustment check the calibration
0.3
according to the instructions above.
2.5
0.2
FORMULAS FOR CALCULATING
1.0
RESULTS
0.2
Conversion of mass to volume
0.7
0.2
V = (w + e) x Z
0.3
V = volume (µl)
0.2
w = weight (mg)
0.6
e = evaporation loss (mg)
0.2
Z = conversion factor for mg/µl conversion
0.3
0.2
Evaporation loss can be significant
0.3
with low volumes. To determine
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