Eppendorf Pipette Reference 2 - Manual (Page 29)

Maintenance
Eppendorf Reference ® 2
English (EN)
29
The existing dispensing volume must be checked before changing the factory calibration or adjustment.
The actual volume can be checked by weighing:
The density of distilled water is approx. 0.9982 mg/μL at 20 °C and 0.9965 mg/μL at 27 °C.
If the set volume is the same as the actual volume, no correction is necessary.
If there is a difference between the actual volume and the set volume of distilled water, please check the
following:
• Is there any liquid dripping from the tip?
• Is the pipette tip fitted leak-proof?
• Is the tip cone undamaged?
• Are the piston and cylinder leak-proof?
Adequate leak tightness is ensured when no drop forms on the pipette tip after aspiration of the nominal
volume with distilled water and a waiting time of approx. 15
s. Hold the pipette vertically without
touching the pipette tip. Prewet the tip several times for nominal volumes ≤ 20 μL.
• Does the temperature of the pipetted liquid correspond to:
– The temperature of the device?
– The ambient air temperature?
• Is the weighing location free of drafts?
• Does the work method and pipetting speed permit complete aspiration and dispensing of the liquid?
• Has the correct numerical value for "Density liquids at weighing temperature" been used to calculate
the actual volume?
• Is the set volume correct?
• For very small volumes (< 10 μL): Is the fine balance sufficiently sensitive (balance resolution:
0.001 mg)?
• Were original epT.I.P.S pipette tips used for testing?
Information on which pipette tip was used as the test tip can be found in the "Technical data"
(see p. 33).
No adjustment changes are allowed unless you can answer all the questions with "yes". In all other cases,
the problems associated with the questions answered with "no" must be eliminated. If the problem is
remedied by exchanging a complete lower part or other parts that affect the volume, proper assembly must
be verified by carrying out a gravimetric test. Information on the systematic and random errors to be met
can be found in the "Technical data" chapter.