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Water analysis with the "Portable Laboratory"
kit
Analytical Chemistry is a strain of chemisry which uses knowledge and
methods from other scientific disciplines, namely from Chemistry, Physics, Biology
and Mathematics, in order to characterize unknown existing systems, through
the measurement of analytical signals from samples.
We are part of a chemical world and understanding the world around us and our material surroundings,
be them natural or manmade, is a permanent challenge.
Analytical Chemists constantly question themselves about the methods, techniques
and strategies that will give them valid analytical results.
The elements can be found in varying abundances and in the form
of various chemical species, ionic or molecular. Our senses often tell us a
lot about the composition of the systems we observe, e.g. through looking
(we look at water and we are quite sure it is water, or better an aqueous solution;
if it is coloured we may know from some characteristic colour that it contains
some specific solute, or smelling (we can distinguish the smell of alcohol/ethanol
from that of ammonia). But in the great majority of cases our senses are
not sensitive enough and additional, more powerful means are required.
Learning Analytical Chemistry implies knowing characteristic properties of
ions and molecules and being able to identify such properties in matrices of
various origins, forms and compositions. Analytical skills can be developed
by exercising scientific and technical knowledge over selected study cases.
Conveniently supervised hands-on approaches can be successful in teaching while
setting the groundwork for progression to higher levels of knowledge and
establishing bridges with a broader scientific culture.
Sophisticated techniques and expensive equipment have to be kept in
conventional laboratories, but often simplified versions can be taken to the
sampling site, instead of bringing the sample to the laboratory.
One of the starting points to the present project has been a “portable laboratory”/”kit”,
developed years ago as part of a graduation project by a group of university
students (Edite Fiúza and Manuela Silva) doing teaching practice to secondary
level pupils. At the time (1986/87) only chemical reactions involving ions were
performed and semi-quantitatively assessed. In the meantime those students
progressed to post graduation, became senior teachers and met again,
working at the same school (Escola Fonseca Benevides - Lisbon). It is a vocational
school with a long standing reputation for training technicians for analytical
chemical laboratories. The “kit” was remembered and dug out of storage
where it had been abandoned. Financial support from the Programme “Science
Alive” of the Portuguese Ministry of Science in the year 2000 motivated
the remaking and upgrading of the “kit”. The number of chemical parameters was
broadened with some qualitative tests turning quantitative and with the addition
of instrumental facilities such as conductivity and potentiometric measurements.
A guidebook accompanies the ”kit”, with protocols for the experiments and bulletins
for reporting results.
The “kit” has been an appreciated companion for students in study
visits where analytical parameters for water quality have been
assessed. It has also been an attraction in workshops with teachers at national meetings.
More schools and MSc students are joining the team, which will introduce
further developments and improvements, including the addition of a spectrophotometer,
allowing optical and spectroscopic measurements. Expansion to computer controlled
experiments with automatic data acquisition and storage will also take
place. An explanatory booklet covering the introduction of fundamentals and the critical assessment of the experiments, is under preparation
and will be available in printed version and electronic form. Comments and suggestions
are welcome.
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