Page 127 - The Veterinary Laboratory and Field Manual 3rd Edition

96 Willy Schauwers

Figure 2.64 Pipette volumetric bunch. Photo: Figure 2.65 Pipette volumetric. Photo: Willy
Willy Schauwers, Provincial Institute for Hygiene, Schauwers, Provincial Institute for Hygiene,
Antwerp, Belgium. Antwerp, Belgium.

There are several types of pipettes: volume that can be measured and the volume
between two consecutive graduation marks
• Bulb pipettes (calibrated to deliver, TD, Ex, are mentioned at the top of the pipette. The
volumetric pipettes) (Figure 2.65) are tubes most common graduated pipette has gradu-
with a wide opening on the upper end, a round ations to the tip: the volume that can be
or oval bulb in the centre, and a tapered tip measured is contained between the 0 mark
on the other end. They are manufactured to and the tip.
deliver a precise volume with a high degree of
accuracy. The volumetric pipette has usually a • Less accurate than bulb pipettes.
single graduation mark. • Calibration: Class AS: ‘Ex + 5s’ or Class
B: ‘Ex’.
• Calibration: Class AS: ‘Ex + 5s’ or Class B: • Usually the nominal (total) volume is
‘Ex’ (5s = 5 seconds waiting time). mentioned at the top.
• Rinse the pipettes with tap water (by using • Rinse the pipettes with tap water (by using
a water jet pump) immediately after use. a water jet pump) immediately after use.

• Graduated pipettes (calibrated to deliver, • Disposable capillary pipettes (calibrated to
TD, Ex) (Figure 2.66) are long tubes with contain, TC, In).
a total capacity marking near the top. The • Mechanical, air-displacement pipettes.

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