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3.
Use of a Pipet
a)
Clean and wash the pipet with water.
b)
Rinse the pipet with 2-5 mL of the solution
to be pipetted and discard the washings.
c)
Repeat step 2.
d)
Fit a squeeze bulb on the top of the pipet.
The squeeze bulb should rest lightly on the top
of the pipet and should not be forced
onto it.
e)
With the tip of the pipet out
of the solution, hold the pipet with your dominant hand and the
squeeze bulb firmly with your other hand
to expel all of the air in the bulb. Put the tip of the
pipet into the solution and slowly release
pressure on the squeeze bulb to allow the liquid to
rise in the pipet past the zero mark and
nearly to the top of the pipet. Then, maintain a
steady pressure on the squeeze bulb so
that liquid stops rising before it is drawn into the
bulb.
f)
Remove the bulb quickly and cover the
top of the pipet with the index finger of your
dominant hand.
g)
Remove the pipet from the solution and
wipe off the outside of the pipet with a paper towel.
h)
Allow the pipet to drain to the zero mark
by gradually releasing the pressure of your finger
on the top of the pipet and gently rotating
the pipet at the top of the solution container.
Continue to keep your finger resting lightly
on the top of the pipet. When the meniscus
reaches the mark, stop the flow of liquid
from the pipet by firmly forming a seal on the top
of the pipet with your index finger.
i)
Touch the tip of the pipet against the
side of the storage bottle to remove any
excess drops and then transfer the pipet
quickly to a new container.
j)
Allow the pipet to drain until the meniscus
reaches the appropriate volume.
Again, apply pressure to the top of the
pipet with your index finger when the meniscus has
reached the correct volume and the liquid
will stop draining.
k)
Touch the edge of the container with
the tip of the pipet to remove the last drop. Then
remove the pipet from the container.
Do not blow out the liquid from the tip of the buret.
l)
Never use your mouth to draw liquid into
a pipet!
