Analysis and Characterization of Manufactured Nanoparticles in Aquatic Environments - Environmental and Human Health Impacts of Nanotechnology - page 252

all methods are validated or even tested for manufactured NPs in relevant envi-
ronmental media but many have shown good potential for NPs in simple media or
for natural NPs in natural waters and soils.
It cannot be emphasized enough that it is necessary to use several methods to
obtain an appropriate level of characterization. But the different methods often
measure different metrics, and sometimes a different variant of the same metric
(Table 6.2). All are equally correct, but not necessarily directly comparable, and a
level of understanding is required by relevant regulatory, industrial and scientifi c
communities; a degree of knowledge exchange as well as fundamental research is
required, too. Further, different methods often have their results skewed to some
extent dependent on the underlying principles or the operating conditions. This
should all be taken into consideration when comparing the results for different
methods. In this chapter, a three-tier physico-chemical characterisation procedure
is suggested for assessing exposure of NPs: based on initial material characteriza-
tion, fate and behaviour characterization in relevant environmental media,
and confi rmation analysis of the exposure conditions during the actual effect
experiments.
For detection and analysis of manufactured NPs in the environment there is still
a major challenge to develop suitable methods. Two promising approaches have
been indicated. One builds on coupling of fractionation methods (e.g. Field-Flow
Fractionation or centrifugation) to a selective and sensitive detection method that
is probing the homogeneous properties of these NPs (e.g. elemental composition,
fl uorescence, shape, etc). The other is to use electron microscopy, but then the
samples need to be pre-fractionated and image analysis would need to be
developed.

6.5 Acknowledgements

The Swedish Environmental Research Council FORMAS, and University of
Gothenburg Nanoparticle platform was funding Hassellöv for this work. I.-M.
Hassellöv is acknowledged for producing illustrations to this chapter.

6.6 References

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