against reference samples, assuming that the earlier
identifications were correct.
PETER FOULKES
Peter Foulkes from ChemGo
unloads chemical waste at
the transfer station
Most of the samples turned out to be quite safe, despite
the labels on the bottles claiming to contain poisons
and disposal won’t be a problem. But Kathrine Haxton,
who ran the work at Keele, thinks it’s a shame that the
bottles in the museum will now be empty.
Following that, A-level students have then gone into
the chemistry department at Keele to run analytical
tests in the lab. The A-level students analysed samples
When asked what the weirdest sample the team found,
Haxton answered easily ‘rhubarb powder.’ Odd now,
but in Victorian times rhubarb powder was used an a
laxative and was so useful that it was more expensive,
by weight, than opium.
Laura Howes
Magnificent molecules
Phillip Broadwith, Chemistry World features editor, highlights one of his favourite molecules.
In this issue: nitric oxide
scrubbers in power plant exhausts
is to reduce these nitrogen oxides
(collectively known as NOx) back to
elemental nitrogen and oxygen.
several nearby cells all at once.
When tissues in the body become
inflamed for long periods of time,
the concentration of nitric oxide
within them increases. This can
NO as a molecular messenger
be used to diagnose disease. It is
The chemistry of nitric oxide inside
particularly useful for monitoring
humans and other mammals is
lung diseases like asthma,
perhaps the most interesting aspect
tuberculosis and even some forms
of this simple molecule’s behaviour.
of lung cancer. As NO can diffuse
NO is involved in controlling blood
through cell membranes easily
pressure – transmitting nerve
and is a gas, it gets breathed
signals and a variety of other
out. By tracking the nitric oxide
signalling processes. Its radical
concentration in patients’ breath,
single electron can also be used as
doctors can keep tabs on the
Nitric oxide is a colourless gas and
a weapon by the immune system
progress of the disease and the
has a single unpaired electron,
to kill invading bacteria. Its role
effectiveness of their treatments.
making it a free radical. On contact
in biology is so significant that
with oxygen it reacts to form brown
Monitoring by mobile
Science magazine proclaimed it
NO2. It coordinates strongly to
their ‘Molecule of the year’ in 1992.
An ideal way to carry out monitoring
transition metals – either using its
single radical electron to make ‘bent’ NO gas is produced within the body would be for each patient to have
a sensor that they could use every
nitrosyl complexes, or donating three by oxidising one of the nitrogen
day. That’s where the chemists are
atoms on the side chain of the
electrons to give ‘linear’ nitrosyls.
Although it has few direct uses itself, amino acid arginine with molecular coming into play. By developing new
kinds of sensors to detect NO, it may
oxygen. This is done by specialised
NO is produced industrially on a
soon be possible to have one built
tonne scale as an intermediate in the enzymes called nitric oxide
into your mobile phone. You can
Ostwald process for producing nitric synthases. When this happens in
the muscular walls of blood vessels, breathe into it and see an instant
acid from ammonia.
this stimulates them to relax so they indication of your health. At the same
Nitric oxide also contributes to
open up and reduce blood pressure. time, the data can be transmitted
air pollution, transforming into
over the mobile phone network to
When NO is produced in nerve
nitrous acid (HONO). Along with
update your doctor’s records.
cells it plays a special signalling
NO2, it is produced by burning
role. Because nitric oxide is a very
So, the baby of the nitrogen oxide
fossil fuels that contain nitrogen
small, uncharged and fat-soluble
family may not be as funny as its big
compounds. One of the main
brother N2O, but it certainly knows
functions of the catalytic convertors molecule, it can diffuse directly
how to get a message across.
in motor vehicles and the chemical across cell membranes and affect
4
JOHN BAVOSI/SCIENCE PHOTO LIBRARY
Nitrogen forms many different
compounds with oxygen, which
have a bewildering array of
chemical properties and biological
action. The brown vapours of
nitrogen dioxide (NO2) are toxic;
whereas nitrous oxide, or N2O, is
used as an anaesthetic. N2O is also
known as ‘laughing gas’ because of
the tendency for people to giggle
uncontrollably after inhaling it. But
it is the simplest of the nitrogen
oxides - nitric oxide or NO - that I
am going to focus on here.
InfoChem
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