CLINICAL LAB SCIENEC

CHAPTER 8: PIPETTING AND USE OF GLASSWARE 197
A
B
FIGURE 8-13 (A) Micropipetters with disposable transfer pipette tips. (B) Using micropipetter behind clear safety shield.
Source: Delmar/Cengage Learning.
will fully evacuate the tip and dispense the liquid. The volume in an adjustable
pipette is variable as the volume in the tip can be changed via a dial or other
mechanism depending on the model. Some pipettes indicate the selected volume
in a small window for reference.
Semiquantitative Pipettes
For the most part, semiquantitative pipettes are not used for accurate measurement
but rather for the general transfer of variable amounts from one tube or
container to another. Some of these pipettes are etched with markings indicating
0.5- to 1.0-mL volumes, but these are not considered as accurate measurements.
They are used only for transfer of approximate volumes of solutions. These basic
disposable pipettes designed for estimated amounts are designed for use with a
rubber bulb that fits tightly on the large end of the pipette or, in some cases, is
built into the pipette. Both types of pipettes are disposable, but the rubber bulb
that is required to be fitted onto the pipette is not disposable.
Pasteur and Beral Pipettes
There are two basic types of semiquantitative pipettes that require the use of a
bulb for aspirating solutions. The differences between these two types of transfer
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