Chemistry Reference
In-Depth Information
refractory elements. These refractory elements can be determined with good sensitivity by ICP OES because
the high temperature that is reached in the plasma. Elements of interest can be detected either simultaneously
or sequentially, make this technique a fast and multi-elemental. ICP-MS is an expensive technique but
combines the fast multi-element features of ICP OES with limits of detection that surpass those of GF AAS
[8, 20, 21].
In multi-component analysis of complex matrices, chromatography is used most often for organic
pollutant determination. Since the mobile phase in HPLC may be a source of pollution, GC should be
chosen whenever possible. However, some 'green' mobile phases (e.g., ethanol-water) can also be used in
HPLC. Since chromatography can determine many components in a single run, the material and energy
input used 'per analyte' is smaller. This makes final analysis by chromatography and foregoing pre-
treatment more beneficial [7].
Additionally, the performance of several methods for water analysis can be improved according to Green
Analytical Chemistry principles in their automation. This approach reduces sample size, and solvent and
reagent consumption become greener than existing methods. Automation can be carried out from a simple
autosampler to complex flow injection analysis (FIA), sequential flow injection analysis (SIA) and multi-
commutation flow systems. These last devices are controlled by a microcomputer and allow the insertion of
samples and reagents only in the instants and in the amounts necessary to implement the analytical procedure,
resulting in minimal reagent consumption [2, 7, 8, 22].
22.3
Green environmental analysis for water, wastewater and effluent
In the quantification of several chemical constituents in natural water (lakes, rivers, oceans, rainwater and
groundwater), waste and effluents are of concern because they can cause environmental damage if their
concentration is modified, being hazardous to biota and affecting the quality of drinking water sources.
Chemical analysis in these aqueous matrices is already well established, and some standard methods
from agencies have been based on classic instrumental techniques. Some methods based on classical
analysis consume large quantities of reagents or energy and frequently generate large volumes of
residuals. These methods often do not present sufficient limits of quantification and sensitivity for
determination of some analytes in concentrations established by recent environmental legislations.
Despite analytical methods based on instrumental techniques modified by electrochemical, spectroscopic
and chromatographic analysis to satisfy some aspects of Green Analytical Chemistry criteria and to
present sufficient analytical characteristics, the classic methods still need improvements to become
environmentally friendly [7-9, 20, 23, 24].
22.3.1
Major mineral constituents
Major mineral constituents are commonly found in the milligram per liter concentration level in natural
water, and the concentrations depend on the mineral deposits in the locality, the anthropogenic action and the
type of natural water (river, sea, rain and groundwater). The major cations are mainly Ca
2+
, Na
+
, Mg
2+
and K
+
,
and the anions are Cl
−
, SO
4
2−
, HCO
3
−
, NO
3
−
, PO
4
3−
and NO
2
−
. Waste and effluents, depending on the
composition, can be sources of pollution by altering these major constituents [24].
Electrochemical detectors can be seen as examples of environmentally friendly analytical approaches
for determining these major constituents. A variety of electrochemical techniques can be used for
environmental analysis. The most common are ion selective electrodes (ISE), an example of which is the
pH electrode, which can be found in all research and routine analytical laboratories. Measurements of
