Dense And Viscous Liquids; Htl Pipette Tips; Recommendations - HTL discovery comfort DV8-10 Handbuch

a film of liquid is formed on the inside wall of the pipette
tip. This film can create an error. Since the film remains
relatively constant in successive pipetting operations
with the same tip, this error can be avoided by forming
the film before transferring the first sample. This is done by
aspirating a sample and dispensing it back into the same
vessel. Since 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

The DISCOVERY Comfort specifications of accuracy
and precision are based on pipetting distilled water. The
handling of liquids with physical qualities of density, vis-
cosity and surface tension differing extremely from water
may need a gravimetrically checked compensation of the
volume setting. Normally the degree of error resulting
from heavy or viscous liquids is negligible if the pipetting
is done slowly and carefully. It is most important to give
the liquids some time to follow 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 re-
sult in accurate values, a compensation could be achie-
ved as follows:
Weigh the liquid pipetted when the DISCOVERY Com-
fort is set to the nominal value. Then calculate the set-off
from the nominal value:
Corr: val. = 2 x nom. val. -
- weight of the sample
m
γ
- density of liquid
Check this operation once again and correct if neces-
sary. Note the corrected value for further pipetting the
same kind of liquid.

6 - HTL PIPETTE TIPS

HTL tips are made from high performance polypropylene
and their quality guarantees the precision and accuracy
associated with the DISCOVERY Comfort. Strict control
is maintained throughout the manufacturing process to
ensure the highest quality.
7
m
-
γ
The accuracy and precision figures for the DISCOVERY
Comfort are only guaranteed when HTL tips are used. The
use of inferior quality tips will seriously degrade the perfor-
mance of the DISCOVERY Comfort.
Tips 10
These tips are used for volumes between 0.1 μl and 10 μl.
They are used with the DV2, DV10, D2 and the D10 models,
which are equipped with the red pushbutton.
Tips 200
These tips are used for volumes between 2 μl and 200 μl.
They are used with the DV20, DV50, DV100, DV200, D20,
D50, D100 and the D200 models, which are equipped
with the yellow pushbutton.
Tips 300
These tips are used for volumes between 50 μl and 250 μl.
They are used with the DV250 and the D250 models,
which are equipped with the green pushbutton.
Tips 1000
These tips are used for volumes between 100 μl and
1000 μl. They are used with the DV1000 and the D1000
models, which are equipped with the blue pushbutton.
Tips 5000
These tips are used for volumes between 1000 μl and
5000 μl. They are used with the DV5000 and the D5000
models, which are equipped with the white pushbutton.
Tips 10000
These tips are used for volumes between 1000 and
10000 μl. They are used with the DV10000 and the
D10000 models, which are equipped with the white
pushbutton.

7 - RECOMMENDATIONS

Observing the following recommendations will ensure
maximum possible accuracy and precision of liquid sam-
pling.
• When pipetting the DISCOVERY Comfort should have
the volume setting locked with the locking ring in the
upper position.
• Make sure to operate the DISCOVERY Comfort slowly
and smoothly.
• The depth of immersion in the sample liquid should be
the minimum necessary and should remain constant
during aspiration.
ENGLISH
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