gilsu north in micropipette Azhar one of
the most commonly used instruments in a
molecular biology laboratory they're
used in conjunction with plastic
disposable pipette tips to measure or
transfer small amounts of liquids
usually from 0.2 microliters to 1000
microliters or one milliliter different
per pets work across different ranges of
volumes and are named by the maximum
volume they pipette the different Pathet
suck very similar so they're labeled on
the top of each push button with a
capital P followed by a number which
indicates the maximum volume for that
particular pipette a p2 pipettes between
0.2 and 2 microliters a p20 per pets
between 2 and 20 microliters a p2
hundred per pets between 20 and 200
microliters and ap1000 per pets between
100 and 1000 microliters a pipette is an
expensive precision instrument improper
use will damage the pipette so correct
use is essential you should never use a
pipette to measure volumes outside of
its range for example using a pea 202
pipette to lower volumes such as 10
microliters or to higher volumes such as
250 microliters will result in
inaccurate volume measurements and will
damage the internal mechanism of the
pipette
each pipette has a vertical row of three
numbers visible in the body of the
instrument to set the volume you can use
either the thumb wheel or on newer
models the push-button this will cause
the three number dials in the body of
the pipette to rotate and change the
volume of liquid that will be taken up
however the dial numbers indicate
different volumes depending on which
pipette is used for example these three
per pets have been set to read the same
numbers on the dial one five two four
the p2 this means that the pipette is
set to a volume of 1.5 to microliters
the bottom two dolls are in red
indicating five tenths and two
hundredths of a microliter for the p20
this means that the pipette is set to a
volume of fifteen point two microliters
the red bottom dollar owes two tenths of
a microliter with the p200 the same
visual setting means that the pipette is
set to a volume of 152 microliters this
p1000 is set to 0-5 two which indicates
a volume of five hundred and twenty
microliters a setting of 100 indicates
the maximum volume for this per pet
which is 1000 microliters the uppermost
number is in red which for this per pet
indicates the number of milliliters
once you've set the volume you need
attach the appropriate pipette tip to
the end of the pipette P 20 and P 200
per pets use the same yellow tips P 1000
per pets use larger blue tips another
type of tip called a filter tip is often
used in the laboratory the sterile
filter within each tip can help to
prevent contamination hold the pipette
with one hand with the narrow side
resting in the palm of the hand add the
pipette tip by gently but firmly pushing
the pipette into the pipette tip which
is held in a tip box you may need a
little practice to learn to apply the
right amount of pressure to give a good
airtight seal between the tip and the
pipette
liquid is drawn in and expelled using
the pipette spartan gently apply
pressure to the button with your thumb
until you feel a natural stop this is
called the first stop the distance you
need to push the push button down will
vary depending on the volume you require
a p20 set to 2 microliters will require
less push-button movement than a p20 set
to 20 microliters so to use the pipette
push the button down to the first stop
then keeping the push button at this
level place the pipette tip about two
millimeters into the liquid you wish to
draw up release the push button by
slowly allowing it to return to its
original position pause for a second to
make sure all the required volume of
liquid has been taken up into the tip
this is especially important when using
more viscous liquids which take longer
to draw up withdraw the pipette tip from
the liquid and place it inside the
recipient container slowly push down on
the push button this will release the
liquid in the pipette tip into the tube
this time pushed beyond the first stop
this ensure that any residual liquid is
expelled from the pipette tip fully
withdraw the pipette tip from the liquid
before you release the push-button so to
recap
push down the push button until you feel
some resistance place the pipette into
the liquid and slowly release the push
button release the liquid from the
pipette by pushing past the first stop
to fully expel the liquid from the
pipette tip into the recipient container
withdraw the pipette from the container
before you release the button
for very small volumes the aspirated
liquid can hang in a drop from the end
of the tip and may not be transferred to
the tube at all so you should touch the
tip to the inside wall of the recipient
container whilst expelling the liquid
once you've aspirated the liquid release
the pipette tip from the pipette by
pressing down on the tip ejector this is
the small white button at the top of the
main body of the pipette be sure that
the attached pipette tip is inside the
appropriate waste container before
pressing the tip ejector a new clean
pipette tip should be used with each new
liquid or if the tip touches any surface
or any liquid other than one your
pathetic if in doubt change the tip
do not use a pipette without a tip
attached liquid should never enter the
body of the pipette it will cause the
pathetic corrode and will be a major
source of contamination between liquids
and experiments do not use a pipette
past its volume limits
this causes pipetting inaccuracies and
also damages the pipette
if you're having trouble attaching a tip
to your pipette don't repeatedly Jam the
pipette into a tip this can damage the
pipette and if the tip doesn't stay on
the end of the pipette simply repeat the
procedure with a new tip when pushing
down the push-button to take up a set
volume of liquid don't push past the
first stop if you push past the first
stop the volume you then take-up will be
too large when taking up liquids don't
simply let go of the push button the
liquid can be sprayed around the inside
walls of the tip and up into the pipette
body causing inaccurate volume
dispensing and pipette contamination
make sure you release the push button in
a controlled manner
if you don't pause after you release the
push button there won't be enough time
for the correct volume to be taken into
the tip air will be taken in instead
also when you're withdrawing a large
volume from a narrow container make sure
the tip stays below the surface
whenever you have liquid in a pipette
tip don't play the pipette down liquid
can get into the body of the pipette
which causes cross-contamination pipette
damaged and inaccurate per petting and
finally remember when per petting small
volumes touch the pipette tip to the
side of the tube to ensure the liquid is
released into the recipient container