38 ProcEssINg TEchNology
Chemical analysis of crystal
growth uses infra-red technique
he creation of reproducible spectrometer is coupled with detailed statistical –
A team of scientists and
crystallisation processes has long or chemometric – data to provide a more detailed
engineers in northern
been a fundamental challenge for analysis of the crystallisation process than has
England have developed
Tdrug manufacturers. However, help is been possible with other infra-red spectrometry
an infra-red based now at hand with a new technique developed by techniques.
technique that gives real
engineers at the University of Leeds in England Mahmud explains: “Using a chemometric
time details about the
that provides real time, detailed analyses of approach enables us to take many more
chemical processes at
chemical processes. parameters into account, which makes it a more
work as crystallisation
occurs.
The technique uses infra-red spectroscopy to reliable predictor of the optimum concentration
monitor supersaturation – the levels of chemical levels required to produce a particular crystal
saturation in a liquid – required for crystallisation structure.”
Une équipe de
to begin to occur (see ‘Monitoring supersaturation’, The work draws on previous research and
scientifiques et over). experimental systems developed through the
d’ingénieurs du nord Most drug compounds are crystalline, Chemicals Behaving Badly II initiative. Led
de l’Angleterre a mis
manufactured in batch process systems. Small by professor Kevin J Roberts at the University
au point une technique
changes in crystallisation process conditions, of Leeds, Chemicals Behaving Badly is an
basée sur l’infrarouge
such as temperature and cooling rates, can Engineering and Physical Sciences Research
qui donne des détails
en temps réel sur les
significantly affect the structure of the resulting Council (EPSRC) and industrial consortium
processus chimiques qui
crystals, something that
interviennent tandis que
affects both their physical
la cristallisation s’opère.
properties and their
performance.
“For example, when you
Ein Team aus
cool water the molecules
Wissenschaftlern
in the water have to get
und Ingenieuren in
into the right position
Nordengland hat ein
Infrarotverfahren
to begin crystallising
entwickelt, das über
into ice crystals and the
chemische Prozesse
temperature can have a
während einer bearing on the size of ice
Kristallisation in Echtzeit crystals that are formed,”
Aufschluss gibt.
says Tariq Mahmud from
the University’s School of
Process, Environmental
and Materials Engineering.
“It’s similar with chemicals,
although there’s a wider
range of parameters to take
into account.”
The new technique uses
a probe attached to an
infra-red spectrometer to
measure the concentration
of a specific chemical in
solution. In laboratory
experiments, this technique
was used on the batch
cooling crystallisation of
chemical L-Glutamic acid
(LGA). The information
gained from the infra-red
www.scientistlive.com
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