Chemistry Reference
In-Depth Information
Table 11.1
Environmental disadvantages associated with the production of atoms for main
atomic spectrometry techniques.
Atom formation
Main atomic techniques
Main environmental disadvantages
Flame
F-AAS, F-AES
High gas consumption (C
2
H
2
, N
2
O)
Gas emission (CO
2
)
Electrothermal
GFAAS
High electric consumption
Moderate gas consumption (Ar)
Plasma
ICP-AES
ICPMS
High gas consumption (Ar)
Plasma
GD-AES
GD-MS
High electric consumption
Object
of
analysis
Analytical
signal
Results
Sample
aliquot
Sample
Calculation
of
results
Sample
preparation
Measurement
Sampling
General
Specific
Figure 11.1
Main steps of a typical analytical procedure.
Similar advantages could apply to plasma-based techniques if the use of microplasmas spreads. Obviously,
the use of such instruments represents a lower environmental impact during their construction as well as
during their operation, opening new ways for miniaturization [13].
A case in which the research phase has proved successful enough to develop commercially available
instruments is high-resolution continuum source atomic absorption spectrometry. This technique permits
monitoring the whole spectrum (190 nm; to 900 nm) with the same lamp (high energy Xe lamp operating in hot
spot mode), thus avoiding the need for using element specific lamps, and therefore reducing the environmental
impact deriving from manufacturing all these lamps [14]. Moreover, this technique also allows for the
monitoring of molecular species, which only need vaporization instead of atomization. Thus, in some cases, it
is feasible to work at significantly lower temperatures, therefore minimizing energy consumption [15].
The second step (sample preparation) is, without question, the one that has received most attention in the
development of Green Analytical Chemistry applications, either from a general point of view [16] or in the
particular field of atomic spectrometry [17], which seems sensible because, on many occasions, this step
represents the main risk for analyte contamination [18]. The various operations included in this step could be
classified in two different areas, even if this classification is not always very simple: (1) general operations,
terms referred to are those that are independent from the technique that will be subsequently deployed to
obtain the analytical signal (e.g., the dissolution of a solid sample); (2) specific operations, when their
execution depends on the use of a particular analytical technique (for instance, the formation of slurries, which
can be directly analyzed by some atomic techniques only). This work will only discuss recent developments
of the second category, since more general developments will be covered in other chapters of this topic.
