Page 111 - The Veterinary Laboratory and Field Manual 3rd Edition

80 Willy Schauwers

used for testing samples, as well as how to cali- • The clear sides should not be allowed to
brate the machine for the calculation of results. become scratched or dirty.
All tests using the spectrophotometer or col- • The clear side of the cuvette should be dry
orimeter should include positive and negative and free from finger marks.
(blank) controls and the equipment should be • Before reading the absorbance or transmit-
calibrated prior to each batch of tests. Standard tance of a coloured solution, check if the
solutions are available for most procedures. solution is clear, there are no air bubbles in
If a laboratory only needs a colorimeter or it, and that it is at room temperature to avoid
spectrophotometer to measure the haemo- condensation on the outside of the cuvette.
globin content in blood, it might be better to • Use a standard and blank with each test.
purchase a dedicated haemoglobinometer. The • Always keep spare lamps in stock.
EKF Diagnostics’ DiaSpect Tm haemoglobinom- • Protect the instrument with a dust cover.
eter is one of the fastest haemoglobin analysers.
DiaSpect Tm delivers laboratory quality results
in just about one second of the microcuvette Microscopes
being placed into the analyser (no reagents
needed) (Figure 2.45). The microscope is the most used tool in a labo-
A few things to remember when using color- ratory therefore it is important that it is used
imeters and spectrophotometers. properly. The cost of a microscope depends on a
number of factors, but in most cases it is worth
• Cuvettes have opaque sides by which they paying a little bit more to get the best quality
should be held and clear sides through which optics and resolution possible.
light is directed. A standard microscope consists of:

• a light source (usually an electric bulb, but
‘field’ microscopes use a mirror to reflect sun-
light)
• a condenser to focus light on the specimen
• a stage with a bracket to move the specimen
• eyepieces through which the specimen is
viewed and which contribute to the magnifi-
cation of the specimen (usually 10×)
• objectives through which light is passed
to the eyepieces and which also contribute
to the magnification of the specimen (usually
10×, 20×, 40× and 100× magnification)
• a course and fine adjustment system to move
the specimen up and down.

The compound light microscope

Figure 2.45 Diaspect Tm handheld haemoglobinom- A compound microscope has a system of lenses.
eter. Photo: Tom Gernaey, Tactilab RDC, Brussels, The lens system nearest the eyes is in the ocular
Belgium. (eyepiece). Another lens system is in the objective,

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