Page 121 - The Veterinary Laboratory and Field Manual 3rd Edition

90 Willy Schauwers

shapes and sizes and is used in specific proce-
dures or preparation of reagents and solutions
used in laboratory analysis. In recent years, it
has become common to use laboratory contain-
ers made from plastic as well as glass. Because
of this, the term laboratory ware or ‘labware’ is
sometimes used to include glassware and plas-
tic ware. Much of today’s labware is designed to
be disposable which eliminates the possibility
of contaminating reagents as a result of inad-
equate cleaning. However, in some parts of the
world, it is too expensive to use disposable plas-
Figure 2.56 Sysmex pocH-100iV Diff screen. Photo: tic ware and a washing and sterilization service
Jan Volkaert, Sysmex-Cyscope, Hoeilaart, Belgium, is required for re-using ‘labware’ (also ecological
© Sysmex.
reasons might apply).
Glassware bottles and volumetric flasks are
Most modern systems rely on flow cytometry, available with exterior amber coating, this fea-
where particles (for example, blood cells) scatter ture is particularly useful when handling reagents
the light directed at them as they pass through a that are light-sensitive. Some glassware bottles
flow chamber. Flow cytometers use the principle are also available with plastic coating to provide
of hydrodynamic focusing to present cells to a protection from mechanical impact and to help
laser (or any other light excitation source). The reduce leakage of the contents should the glass
sample is injected into the centre of a flow cham- break. The maximum working temperature for
ber so that the stream of particles in the sample these bottles is 135°C but long-term exposure
is very narrow allowing each particle to contact (> 30 min) should be avoided. Avoid expo-
the laser individually. As the cells intercept the sure to direct heat from a hotplate or a Bunsen
light source they scatter light and fluorochromes flame.
are excited to a higher energy state. This energy Glass containers in laboratories are of two
is released as a photon of light with specific prop- basic compositions.
erties (depending on the fluorescent dye used) Flint glass:
and this can be recorded. Unlike spectrophotom-
etry, which measures the percent absorption and • flint glass has a low resistance to heat and
transmission of specific wavelengths of light for chemicals but it is inexpensive.
the whole sample, flow cytometry measures the
fluorescence per cell (or particle). Cytometry is Borosilicate glass:
a useful research tool and is widely used in more
specialized veterinary diagnostic laboratories. • usually has a high thermal resistance and
does not react with most chemicals, Pyrex is
a brand of borosilicate glass commonly used
2.6 General laboratory ware for beakers, flasks and other labware
• contains a higher percentage of SiO than
2
All laboratory procedures require the use of flint glass – glass with a high percentage
some type of container, often glassware (Figure weight (> 80%) of silica (SiO ) is less likely
2
2.57). Basic laboratory glassware comes in many to be attacked by acids (with the exception of

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