Environmental Engineering Reference
In-Depth Information
9.3 SELECTION OF THE PROPER ATOMIC
SPECTROSCOPIC TECHNIQUES
It is not always intuitive for a beginner to choose appropriate atomic spectroscopic
techniques for a specific type of elemental (metal) analysis. In the relatively small
settings of analytical and environmental labs, analysts really do not have many
options and are forced to use whatever instruments are available. In other cases, such
as in commercial labs, the analysts may have various instrument options to choose
by deciding which technique is optimum to meet a particular analytical need. A
clear understanding of the analytical problem and the capability provided by dif-
ferent techniques are therefore necessary. Important factors include detection limits,
analytical working range, sample throughput, cost, interferences, ease of use, and
availability of proven methodology. These are summarized below in Sections 9.3.1
and 9.3.2 for the comparison of FAA, GFAA, ICP-OES, and ICP-MS. Technical
details of ICP-MS will be described in Chapter 12. As a semiquantitative tool,
XRF is excluded in the following comparison; its environmental applications and
limitations have been briefly discussed in the previous section.
9.3.1 Comparison of Detection Limits and Working
Range
A low detection limit is essential for trace analysis of metals. Without adequate
detection limit capabilities, lengthy sample preparation (concentration, extrac-
tion, and so forth) for the manipulation of the analytes may be required prior
to analysis. In general, the detection limits are in a decreasing order of: FAA
>
ICP-OES (radial)
>
ICP-MS (Fig. 9.9). FAA is the least sensitive, and ICP-MS is the most sensitive.
>
ICP-OES (axial)
>
hydride generation AA
>
GFAA
Figure 9.9
Typical detection limit ranges for the major atomic spectroscopy techniques (Courtesy
of Perkin-Elmer, Inc.)
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