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Chapter 4: Discussion
4.1 Method Optimisation
In order to obtain optimum results many variations of the method were
attempted including different sizes of colloid (51,64, 90 nm) Different nose
cones used and no nose cone attached. Sampling from the supernatant instead
of the pellet after centrifugation was also attempted.
For the Truscan run
different methods attempted included drying the sample on a glass slide at
room temperature, pipetting the sample into a capillary tube and focussing the
laser down the length of the capillary tube or focussing it through glass of the
capillary tube. The glass slide and capillary tube gave the same large glass
hump with no peaks present in the spectra so were not suitable.
4.2 Library
Creating the library to gain reference spectra was a time consuming process. It
could take up to several hours to obtain a single reference spectra or signature,
as referred to in the TruScan’s manual. For use in the field, the maximum
amount possible of controlled substances would have to be added to the library.
As the results of this study show, once cutting agents and adulterants are
added, it is not always likely that the TruScan software will report the result as
the controlled substance present in the sample. For this reason a library of
common cutting agents and adulterants should be included also, further adding
to the time consuming process. The controlled drug may not be reported by the
software but the cutting agent result gives a clue it is likely an illicit drug is there.
This however requires inspection of the spectra on Omnic software on a PC and
this cannot be performed on the TruScan device.
The TruScan manual claims the installed software; DecisonEngine on the
device takes environmental factors such as light into consideration when a
spectra is being obtained. However, covering the sample up whilst the laser is
on, reduces the time taken. This study used items as black weighing boats to
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