Environmental Engineering Reference
In-Depth Information
(4-MBC), m-toluamide, galaxolide, tonalide, musk xylene, musk ketone, celes-
tolide, triclosan, octocrylene and two alkylphenol surfactants such as p-octyl-
phenol and p-nonylphenol. These methods consisted of extraction, clean-up,
derivatization and analysis by gas chromatography-mass spectrometry with
selected ion monitoring (GC-SIM-MS) or gas chromatography-tandem mass
spectrometry (GC-MS/MS) techniques (Mottaleb et al.
2009
). To assess recovery
of target compounds from 1-g tissue homogenates, acetone was selected as opti-
mal solvent for extracting compounds with dissimilar physicochemical properties
from fish tissue. Initial experiments confirmed that GC-SIM-MS could be applied
for analysis of lean fillet tissue (<1 % lipid) without gel-permeation chromatog-
raphy (GPC), and this approach was applied to assess the presence of target ana-
lytes in fish fillets collected from a regional effluent-dominated stream in Texas,
USA. Benzophenone, galaxolide, tonalide, and triclosan were detected in 11 of 11
environmental samples at concentrations ranging from 37 to 90, 234 to 970, 26
to 97, and 17 to 31 ng g
−
1
, respectively. However, performance of this analytical
approach declined appreciably with increasing lipid content of analyzed tissues.
Successful analysis of samples with increased lipid content was enabled by add-
ing GPC to the sample preparation protocol and monitoring analytes with tandem
mass spectrometry. Both analytical approaches were validated using fortified fil-
let tissue collected from locations expected to be minimally impacted by anthro-
pogenic influences. Average analyte recoveries ranged from 87 % to 114 % with
RSDs <11 % and from 54 % to 107 % with RSDs <20 % for fish tissue contain-
ing <1 % and 4.9 % lipid, respectively. Statistically derived method detection lim-
its (MDLs) for GC-SIM-MS and GC-MS/MS methodologies ranged from 2.4 to
16 ng g
−
1
, and from 5.1 to 397 ng g
−
1
, respectively (Mottaleb et al.
2009
). In
a following study, improvement of the MDL has been observed between 12 and
38 ng g
−
1
by the GC-MS/MS methodology for the same PCPs using 2.0-2.5 g of
fish (Subedi et al.
2011
).
9 Does DOM Act as Energy Source for Living Organisms
and Aquatic Ecosystem?
The concentration levels of DOC in groundwater are very variable: they reach
16-424
μ
M C in Asia, 42-15333
μ
M C in Europe, 8-2333
μ
M C in North America,
1108
±
217-14167
±
6333
μ
M C in Botswana (Africa), 100-3000
μ
M C in Brazil
(South America) (Table
2
) (Mostofa et al.
2007a
, Mostofa KMG et al., unpub-
lished data; Buckau et al.
2000
; Bertilsson et al.
1999
; McIntyre et al.
2005
; Meier
et al.
2004
; Crandall et al.
1999
; Schwede-Thomas et al.
2005
; Pabich et al.
2001
;
Michalzik et al.
2001
; Anawar et al.
2002
; Richey et al.
2002
; Bradley et al.
2007
).
Groundwater is the main source of drinking water for many developing and devel-
oped countries, including the USA. Groundwater has the advantage over surface
water of being usually free of suspended solids, bacteria and other disease-causing
microorganisms (Mostofa et al.
2009a
). Interestingly, upland areas make up 30 %
