Pre-Rinsing; Dense And Viscous Liquids; Pipette Tips - bioSan Assist Serie Manual De Instrucciones

Avoid touching the opening of the tip.
Dispensing:
• Place the end of the tip against the inside wall of the vessel
at an angle of 10° to 40°.
• Press the pushbutton smoothly to the first stop, (Fig. 2C).
Wait one second.
• Press the pushbutton to the second stop to expel any re-
maining liquid, (Fig. 2D).
• Keeping the pushbutton depressed to the very end, remove
the pipette by drawing the tip against the inside surface of
the receiving vessel.
• Release the pushbutton to its starting position, (Fig. 2E).
• Eject the tip by pressing the tip ejector button, (Fig. 2F).
Remember to change the tip whenever a different kind of
liquid is to be sampled.
Filters
A replaceable filter, fitted in a seat in the bottom part of the
shaft, is used in 5,000 µl and 10,000 µl pipettes (Fig. 3L).
This filter prevents the aspirated liquid from entering into
the shaft and thus from contaminating the inside of the shaft
and the piston. Using the filter is particularly important when
aspirating and dispensing large volumes of liquid.
If the filter becomes wet during liquid aspiration it should be
replaced with a new one.
4 – PRE-RINSING
When pipetting liquids of higher viscosity or lower surface
tension than water (e.g. sera or organic solvents), a film of
liquid is formed on the inside wall of the pipette tip. This film
can create an error. As the film remains relatively constant in
successive pipetting operations with the same tip, this error
can be eliminated by forming the film before transferring
the first sample. This is done by aspirating a sample and
dispensing it back into the same vessel. Now, as the film is
already formed, all of the following samples will have better
accuracy and repeatability.
This pre-rinsing operation should be repeated when the
volume to be aspirated is changed or when a new tip is used.
5 – DENSE AND VISCOUS LIQUIDS
Assist pipette specifications of accuracy and precision are
based on pipetting distilled water. Handling of liquids with
physical qualities of density, viscosity and surface tension
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which differ substantially from water may need gravimetrically
checked compensation of the volume setting. Normally the
degree of error resulting from heavy or viscous liquids is
negligible if pipetting is done slowly and carefully. It is most
important to give the liquids some time to react to the change
of pressure by holding the pipette tip in its position for at least
2 sec. after the aspiration and the blow out stroke.
If in extreme cases, this method of operation does not result in
accurate values, a compensation may be achieved as follows:
Weigh the liquid pipetted when the Assist pipette is set
to the nominal value. Then calculate the set-off from the
nominal value:
Correction, value = 2 x nominal val. m —
m – weight of the sample
γ – density of liquid
Check this operation once again and correct if necessary.
Note the corrected value for further pipetting of the same
kind of liquid.
6 – PIPETTE TIPS
Our recommended tips are made from high performance
polypropylene and their quality guarantees the precision and
accuracy associated with the Assist pipette. Strict control is
maintained throughout the manufacturing process to ensure
the highest quality.
The accuracy and precision figures for the Assist pipette
are only guaranteed when our recommended tips are used.
The use of inferior quality tips will seriously degrade the
performance of the Assist pipette.
Tips 10
These tips are used for volumes between 0.1 µl and 10 µl.
They are used with the AP2, AP10, AP8-10 & AP12-10
models.
Tips 200
These tips are used for volumes between 2 µl and 200 µl.
They are used with the AP20, AP50, AP100, AP200, AP8-50,
AP12-50, AP8-200 and AP12-200 models.
Tips 300
These tips are used for volumes between 50 µl and 300 µl.
They are used with the AP250, AP8-300 and AP12-300
models.
ENGLISH
γ
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