Aspirating And Dispensing Liquids; Aspirating Liquids; Dispensing Liquids; Pre-Rinsing - VWR UHP Mode D'emploi

• The tips should be replaced with new ones if:
- a different type of liquid is handled;
- a different liquid volume is dispensed;
- visible droplets of liquid remain in them.
• Pipetted liquid should not enter the pipettor shafts. To
ensure this:
- press and release the pipetting pushbutton slowly
and smoothly;
- do not put the pipettor away if there is any liquid in
the tips;
- do not invert the pipettor;
- do not set and aspirate volumes exceeding nominal
values.
• Before aspirating liquid of temperature that differs from
ambient temperature, it is recommended to rinse the
tips several times with the aspirated liquid.

4. ASPIRATING AND DISPENSING LIQUIDS

4.1 ASPIRATING LIQUIDS

A B C
Fig. 4
• The pipetting pushbutton (fig. 1A) should be pressed to
the first stop (fig. 4A),
• While holding the pipettor in a vertical position, tips
should be immersed into the aspirated liquid to the
depth of 2 to 4 mm, and flushed once by drawing
a dose of liquid and dispensing it out with slow and
steady movement. The tips may aspirate air if immersed
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D E F
to a depth lower than recommended or if the pipetting
pushbutton is released quickly,
• To aspirate liquid release the pipetting pushbutton
smoothly (fig. 4B),
• Wait for about 1 second before withdrawing the tips
from the aspirated sample, fig. 4.
WARNING! Do not touch the used tips.

4.2 DISPENSING LIQUIDS

• While holding the pipettor slightly inclined from 10 to
40° off the vertical, place the tips orifice against the
inside wall of the receiving vessel.
• Then, press the pipetting pushbutton smoothly to the
first stop, dispensing the liquid (fig. 4C).
• After about one second press the pipetting pushbutton
to the final stop, blowing out the remaining liquid from
the tips (fig. 4D).
• Holding the pushbutton depressed remove the pipettor,
drawing it against the vessel inner wall.
• Release the pipetting pushbutton to its starting position
(fig. 4E) and eject the tips by pressing the tip ejector
button (fig. 4F).
CAUTION: Replace the tips with a new one whenever a
different liquid is to be pipetted.

4.3 PRE-RINSING

When pipetting liquids of viscosity higher or surface
tension lower than those of water (e.g. serum or organic
solvents) a film of liquid is formed on the inside wall
of the pipetting tips. The film can create an error. Since
the film remains relatively constant in successive pipetting
operations with the same tips, this error can be avoided
by forming the film before the first pipetting. This is done
by performing a full pipetting cycle of a liquid into the
same vessel. After such a procedure, the film of liquid is
already formed in the tips and ensures better accuracy
and repeatability of successive pipetting operations.

4.4 ASPIRATING HIGH DENSITY LIQUIDS

The accuracy errors provided in Table 1 have been
determined using distilled water. When pipetting liquids
whose properties (density, viscosity, surface tension)
differ from the properties of water, it may be necessary to
compensate for volume settings.
ENGLISH
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