Monitoring Performance; Changing The Membrane - R-Biopharm KOBRA CELL Instruction Manual

Monitoring Performance

6.3
It is necessary to regularly monitor the performance
of the KOBRA® CELL in order to detect any
deterioration in the membrane contained within.
The performance should be checked at the time of
installation and then weekly by comparing the peak
areas of a known aflatoxin standard. The same should
also be done in order to monitor the deterioration of
the lamp in the detector.
Deterioration of the membrane will occur over a
period of time depending upon the frequency of use
and the type of samples analysed (Fig. 7). When the
performance becomes unacceptable the
should be replaced (Product Code: K02).
Normally, it is found that even under extreme
workloads the membrane does not need to be
replaced for at least 6 months or 1,000 injections.
Fig 7. Deterioration of KOBRA® CELL Membrane

Changing the Membrane

6.4
Change the membrane when a decrease in
performance is observed which cannot be attributed
to the detector lamp. Additional membranes are
available separately (K02).
1. Using a screw driver take off the white plastic
housing of the KOBRA® CELL by removing the
6 locating screws.
2. Carefully separate the top white plastic housing,
and remove in turn the internal layers of the cell
using tweezers. Make a note of the position and
orientation of each layer as it is removed.
3. Continue removing the internal layers until the
membrane is exposed. Before removal inspect
the membrane for damage, discolouration and
membrane orientation. During the life of the KOBRA® CELL
the bromination reaction causes the centre of
the membrane to lose it's colour. No holes
should be visible in the membrane other than
the pre-cut holes for the locating pins at either
end of the membrane. Note the orientation of
the membrane.
4. Remove the membrane from the KOBRA® CELL
ready for replacement using tweezers.
5. Carefully remove the spare membrane, holding
it by one end with the tweezers rather than the
middle.
6. Position the replacement membrane over the
different sized locating pegs, according to the
size of pre-cut holes in the membrane.
Caution: Do not allow the membrane to dry
out. Add distilled water if necessary.
7. Carefully replace the layers to be positioned on
top of the membrane, remembering their correct
order and orientation.
8. Secure the layers using the 6 locating screws.
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