The book covers a critical compilation of analytical methods used
for the monitoring of pesticides and their degradation products in
water. It contains up-to-date material and is the direct result of
the authors' experience in the field of pesticide analysis. The
book is structured in six chapters, starting from general aspects
of pesticides like usage, physicochemical parameters and occurrence
in the environment. A second chapter is devoted to sampling from
water matrices, stability methods of pesticides in water and
quality assurance issues. The general chromatographic methods for
pesticides are reported, including the newly developed
electrophoresis methods and GC-MS and LC-MS confirmatory analytical
methods. Sample preparation methodologies, including off-line and
on-line techniques are described in the next two chapters, with a
comprehensive list of examples of pesticides and many metabolites,
including the use of different GC-methods and LC-methods. The final
chapter is devoted to the development of biological techniques,
immunoassays and biosensors, for the trace determination of
pesticides in water samples.
The book answers one of the key problems in pesticide analysis:
the diversity of chemical functional groups, with varying polarity
and physicochemical properties. Pesticides and their metabolites
have received particular attention during the last few years in
environmental trace-organic analysis. For instance, in the case of
groundwater, the use of pesticides has become a cause for concern.
Under the right conditions, pesticides, such as fertilizer
nitrogen, can move through the soil into groundwater, a phenomenon
once thought improbable. The movement of agrochemicals in surface
water flow can be, in some instances, a major problem, specially in
the case of water soluble pesticides that are generally transported
to estuarine and coastal waters. Estuarine waters feature gradients
of both pollutant concentrations and physicochemical
characteristics such as salinity, turbidity and pH, and all these
parameters must be carefully considered when developing methods of
analysis for trace organics in estuarine waters.
One of the key parameters in analytical determination is the
environmental sampling. Different protocols and devices are needed
for sampling sea-water samples - usually using large sample volumes
of more than 50 litres either with LLE or SPE, with the problems
encountered due to dissolved and particulate matter - which is
different from drinking water and well water sampling. The
representativeness of the sampling is also of concern.
The sample preparation of organic compounds from water matrices
has been recognized to be a bottleneck and it has been
traditionally neglected in the literature. We should comment
following R.W. Frie's ideas - that the most sophisticated hardware
is useless if the chemistry in the protocol does not work. During
the last few years new adsorbents have appeared - carbon type,
polymeric sorbents with high capacity and immunosorbents - which
can more efficiently trap the more polar compounds.
The development of advanced automation methods based, usually on
solid phase extraction techniques - PROSPEKT, OSP-2 and ASPEC XL -
are examples of commercially available equipment that are of
growing importance. These systems are generally coupled to LC and
GC techniques.
Sampling and sample handling can not be regarded as separate
techniques in the analytical process and both should be integrated
into the whole analytical determination. For this reason,
validation and confirmation methods, such as mass spectrometry,
either GC-MS and/or LC-MS, are needed. These serve to check the
quality assurance of the developed method. The discussion between
multiscreening versus specific methods of analysis and the
influence of the matrix (ground-, surface- and estuarine-water), is
also a point of concern due to the diversity of chemical classes
within the compounds of study.
Finally the use of rapid methods of analysis, which refer
basically to biological techniques, biosensors and immunoassays are
also of growing interest for the determination of pesticides in
environmental matrices. The rapid development of these techniques,
being more sensitive and that can work at different pH and drastic
environmental conditions, like very different pH and salinity
values, makes that these methods are very useful and complementary
to conventional GC and/or LC techniques for the determination of
pesticides.
General
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