Thermo Scientific F1-ClipTip User Manual page 10

The performance of a new and serviced pipette must be checked and documented.
The manufacturer's specifications should be used as guidelines and the user should establish
acceptable imprecision and inaccuracy performance limits (ISO 8655).
The user determines the performance and applicability of the pipette and tip combination
for a particular application and determine the required interval for performance checking.
Before starting the actual dosing, pre-rinse the tip with the liquid by filling and emptying the
tip three to five times to improve accuracy and precision.
6.2 Test conditions and equipment
An analytical balance must be used. The scale graduation value of the balance should be chosen
according to the selected test volume of the pipette:
Volume range
under 10 µl
10 100 µl
–
above 100 µl
The test liquid is deionized distilled "grade 3" water in compliance with ISO 3696. Tests are done in a
draft-free room at a constant (±0.5°C) temperature between 15°C to 30°C. The relative humidity must
be above 50%. Especially with volumes under 50 µl, air humidity should be as high as possible to reduce
the effect of evaporation loss. Special accessories, such as an evaporation trap, are recommended.
6.3 Procedure to check calibration
The pipette is checked at maximum volume (nominal volume) and minimum volume (or 10% of the
maximum volume). A new tip is first pre-wetted three to five times and a series of ten pipettings
is done at both volumes. A pipette is always adjusted according to the delivery of the selected
volume. Use of the forward pipetting technique is recommended. The maximum permissible errors
are valid for the forward pipetting method. It is recommended to use the ISO8655 calibration limits in
Appendix 3 or user-defined specifications.
Procedure:
1. Do 10 pipettings at the minimum volume (or 10% of the maximum volume).
2. Do 10 pipettings at the maximum volume.
3. Calculate the inaccuracy (A) and imprecision (CV) of both series.
4. Compare the results to the limits.
If the calculated results are within the selected limits, the adjustment of the pipette is correct.
Pipette adjustment
Adjustment is done only for one volume. The recommended adjustment volume is the minimum
volume or 10% of the maximum volume.
1. Fit the service tool (Picture 7) 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 according to
the instructions above.
Formulas for calculating results
Conversion of mass to volume
V = (w + e) x Z
V = volume (µl)
w = weight (mg)
e = evaporation loss (mg)
Z = conversion factor for µl/mg conversion
Evaporation loss can be significant at low volumes. To determine mass loss, dispense water into the
weighing vessel, note the reading and start a stopwatch. Check and note down how much the reading
decreases during 30 seconds (e.g. 6 mg = 0.2 mg/s).
Compare this to the pipetting time from taring to reading. Typically , the pipetting time might be 10
seconds and the mass loss is then 2 mg (10 s x 0.2 mg/s in this example). If an evaporation trap or lid
on the vessel is used, the correction of evaporation is usually unnecessary.
Readable graduation
0.001 mg
0.01 mg
0.1 mg
10
Picture 7