Page 107 - The Veterinary Laboratory and Field Manual 3rd Edition

76 Willy Schauwers

have the advantage that large quantities of cool- • air-displacement automatic mechanical
ing water are not required. pipettes:
If it is necessary to provide ultra-pure water
(as in some central and reference facilities or • recommended for aqueous samples and
research establishments), then water can be for general laboratory work
double distilled or, deionized first and then • always have a cushion of air (dead vol-
distilled. In laboratories with poor electricity ume) between the pipette piston and the
supply, a deionizer is a good alternative for a liquid sample
distilling apparatus. • the piston is a permanent part of the
pipette

automatic mechanical pipettes and • positive displacement automatic mechanical
dispensers pipettes:

There are two types of automatic mechanical • recommended for problem samples (vis-
pipettes (Figures 2.40 and 2.41): cous, dense, volatile, radioactive, corrosive)

Figure 2.40 Air-displacement pipette. Photo: Gilson, Figure 2.41 Positive displacement pipette. Photo:
Den Haag, courtesy of Gilson International BV. Gilson, Den Haag, courtesy of Gilson International BV.

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