Aspirating And Dispensing Liquids; Pre-Rinsing; Dense And Viscous Liquids - CORNING Lambda Plus Instruction Manual

LAMBDA PLUS LB-04-2010

3 - ASPIRATING AND DISPENSING LIQUIDS

Place a tip on the shaft of the pipettor. See Section 6 for
the appropriate tip. Press the tip on firmly using a slight
twisting motion. This will ensure an airtight seal.
Important: Never aspirate liquids into the Lambda
Plus single-channel pipettor without a tip attached.
Aspiration
Press the pushbutton to the first positive stop, (Fig. 2A).
Holding the pipettor vertically, immerse the tip into the
sample liquid. The depth to which the tip is immersed in
the sample liquid depends on the model.
Model
2
10
20, 100
200 1000
Release the pushbutton slowly and smoothly to aspirate
the sample, (Fig. 2B). Wait one second and then withdraw
the tip from the liquid. If the pipet tip is not immersed to
the recommended depth or if the pipetting pushbutton is
rapidly released, air may enter the disposable tip.
Avoid touching the orifice 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
remaining liquid (Fig. 2D).
• Keeping the pushbutton depressed to the very end,
remove the pipettor 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.
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Immersion depth (mm)
≤ 1
≤ 1
2 – 3
2 – 4
21-04-10 15:31 Page 10

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 pipet 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

™
Lambda Plus single-channel pipettors specifications of
accuracy and precision are based on pipetting distilled
water. Handling of liquids with physical qualities of densi-
ty, viscosity and surface tension which differ substantially
from water may need gravimetrically checked compensa-
tion 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 impor-
tant to give the liquids some time to react to the change
of pressure by holding the pipettor 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 pipettor when the Lambda
single-channel pipettor is set to the nominal value. Then
calculate the set-off from the nominal value:
Correction, value = 2 x nominal. val. -
- weight of the sample
m
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.
™
Plus
m
- γ
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