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quantification were 11.9 and 39.6 ng mL
-1
, respectively, approximately 5 times
lower than those reported for HPLC with UV detection (Casal et al 1998) and
similar to other LC-MS methods (Zhu et al 2004). The method applicability
was evaluated by the analysis of different types of coffee available in the
market (green and commercial samples of regular and decaffeinated roasted
and instant coffees, roasted to different degrees). The method showed to be
suitable, thus presenting as a fast and reliable alternative method for routine
coffee analysis.
d
n
0
t
2
n
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3
7.2.2 Water
It is well known that the source, presence, and destiny of pharmaceutical
compounds in the aquatic environment are of concern. These compounds may
be excreted unmetabolized or partially metabolized by humans, resulting in
their eventual passage into the environment. Monitoring the infiltration of
domestic wastewater and untreated sewage into aquatic ecosystems has been a
crucial challenge for environmental agencies whose efforts are devoted to
protect
the
delicate
balance
between
biological
systems
at
risk
and
the
inevitable urban colonization, especially of coastal areas.
To unequivocally distinguish the contributions of different sources to the
overall contamination found in specific ecosystems, molecular tracers, which
are unique chemical compounds, can be used. Since caffeine is ranked number
one drug worldwide, it may be used for this purpose, providing a potential way
of tracing human-derived wastewater intrusions in coastal ecosystems by
analyzing the concentrations of caffeine in surface and ground water.
HPLC-UV methods are inadequate for the analysis of caffeine in water since
they show inadequate detection limits (in the order of 0.05 ppb) to properly
determine the trace amounts of caffeine likely to be found in environmental
samples (in the order of low ppt). In this sense, due to its high sensitivity, LC-
MS is the method of choice for the analysis of trace levels of caffeine in surface
waters.
Gardinali and Zhao (2002) developed a new LC-MS method using
atmospheric pressure chemical ionization (APCI) to determine trace amounts
of caffeine in surface water. The method allowed the determination of caffeine
at levels as low as 4.0 ng L
-1
(ppt) in both salt and freshwater. Sample
preparation entailed membrane filtration, addition of deuterated atrazine as
internal standard, liquid/liquid extraction with methylene chloride, evapora-
tion of the organic solvent and reconstitution in mobile phase.
Chromatographic separation was achieved on a C18 column using gradient
elution with water and methanol. Quantitative determination of caffeine in the
final extracts was carried out by APCI in positive mode under SIM (ions with
m/z 195 and 196).
More recently, LC-MS-MS, which shows higher selectivity and sensitivity
than LC-MS, has been employed for the analysis of trace levels of caffeine in
water
samples.
However,
matrix
effects
pose
a
great
challenge
for
the
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