CLINICAL LAB SCIENEC

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ESSENTIALS OF CLINICAL LABORATORY SCIENCE
pipettes lies in the fact that one uses a separate rubber
bulb for aspiration, while the other uses a single piece
pipette with the aspirator bulb built into the pipette.
The Pasteur pipette (Figure 8-14) uses a separate rubber
bulb for aspirating solutions for transfer from one
FIGURE 8-14 Pasteur pipette, disposable.
container to the next. Pasteur pipettes are not calibrated
for any particular volume and are essentially
Source: Delmar/Cengage Learning.
large droppers that can be used to remove liquid from
one container and add it to another. It is not necessary
to use a different Pasteur pipette for each test
when placing drops of a specific reagent into a number of tubes or other containers.
The Pasteur pipette can potentially be reused unless it becomes chipped or
contaminated during the procedure.
The second type, the Beral pipette, is a one-piece pipette, usually made
from flexible soft plastic (polyethylene) that has a built-in bulb on the end (Figure
8-15). Where accurate measurement is not required, the soft plastic bulb
can also be filled with fluid to obtain larger volumes than the stem itself would
accommodate.
Characteristics of Semiquantitative Pipettes
Originally, pipettes were made of glass and were not disposable. The disposable
pipettes in use currently are more common in chemistry procedures when using
aqueous solutions. Glass and plastic graduated serological pipettes that may be
disposable, as well as disposable Pasteur pipettes, require the use of some kind
of additional suction device (Beral pipettes have a built-in suction bulb). This
is typically a pipette bulb, which is a rubber bulb that sucks the liquid into the
pipette by negative pressure and also allows one to drain the pipette in a controlled
fashion. Pasteur pipettes may also be known as droppers or eye droppers
A
B
FIGURE 8-15 (A) Beral disposable one-piece pipettes may come individually wrapped when clean or sterile pipettes are required.
(B) For general use that does not require sterility, Beral pipettes come in bulk packages.
Source: Delmar/Cengage Learning.
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