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36
Problem
2. Non-specific
background
over whole of
filter
Possible cause
4. Loss of dNTP
during
evaporation
1. Presence of
unincorporated
label
Remedy
4. If the dNTP solution
has been evaporated
to dryness prior to
use, handling losses
may have occurred.
Check this loss has
not occurred during
lyophilization of the
solvent, during
transfer of the
reconstituted
dNTP solution or
by adsorption of the
dNTP onto the walls
of the tube. If
necessary the
reconstituted dNTP
solution may be
counted and an
adjustment made
before setting up the
labelling reaction.
1. Unincorporated
nucleotides can give
high backgrounds.
Remove by Sephadex
G-50 spin columns
or ethanol
precipitation (see
page 32 for protocol)