# Council Directive 98/57/EC of 20 July 1998 on the control of Ralstonia solanacearum (Smith) Yabuuchi et al., Appendix 5: Determination of contamination level in IF and FISH tests

Extent: E+W+S+N.I.

1.. Count the mean number of typical fluorescent cells per field of view (c).
2.. Calculate the number of typical fluorescent cells per microscope slide window (C).
C = c × S/s
where
S
=
surface area of window of multispot slide
and
s
=
surface area of objective field
s = πi 2 /4G 2 K 2
where
i
=
field coefficient (varies from 8 to 24 depending upon ocular type)
K
=
tube coefficient (1 or 1,25)
G
=
magnification of objective (100 ×, 40 × etc.).
3.. Calculate the number of typical fluorescent cells per ml of re-suspended pellet (N).
N = C × 1 000 /y × F
where
y
=
volume of re-suspended pellet on each window
and
F
=
dilution factor of re-suspended pellet.

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Source: https://www.legislation.gov.uk/eudr/1998/57/annex/II/appendix/5 (the official version)
Page: https://openlegislation.uk/eu-directive-1998-57/annex-II/appendix-5
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.