Page 49 - Volume 1, Issue 2, July 2008
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GS/MS/MS determination of PAHs in water
101
4. Instrumentation
A Varian CP-3800 gas chromatogra-
phy system, interfaced to a triple quadru-
pole mass spectrometer (Varian 1200 L)
was used for the residues identification
and quantification. The identification and
quantification of the studied analytes was
carried out, based on the technique of MS/
MS using the transitions (precursor ion –
product ion, Multiple Reaction Monitoring
– MRMs), which are presented in Table 1.
The GC was equipped with a split/splitless
injector operating in the splitless mode
and an autosampler CP-8400. The analyti-
cal capillary column used was a 30 m x 0.25
mm I.D., coated with 0.25 μm film thick-
ness, VF-5 ms (Varian 25200 Commercen-
tre Drive, Lake Forest, CA, U.S.A.). The oven
temperature program consisted of 2 min
hold at 70
o
C, ramp at 30
o
C/min to 180
o
C,
1.8
o
C/min to 230
o
C, 30
o
C/min to 280
o
C and
a final hold for 30min. The injector was op-
erated at 300
o
C, pulse pressure 10 psi and
pulse duration 0.25 min. The carrier gas
was He at 1ml/min. The injection volume
was 1 μl. The temperature of the source
was 200
o
C, the interface temperature at
290
o
C and the solvent delay 5 min.
Quantification in this method was
made by comparing the peak areas of the
sample solutions to the peak areas of two
analytical standard solutions bracketing
the area of the sample and not differing in
concentrations more than 20% from each
other, thus not using a calibration curve.
Results and Discussion
The substances benzo [a] anthracene,
benzo [b] fluoranthene, benzo [k] fluoran-
thene, benzo [a] pyrene and indeno [1,2,3-
cd] pyrene have been classified as priority
pollutants (4), a fact that makes their de-
tection and determination in water nec-
essary. Furthermore fluoranthene is an
indicator substance and its presence in a
water sample is taken as evidence for a
PAHs contamination of the water.
In the present study an effort has been
made to adjust an already existing meth-
od, routinely used in our laboratory for
Table 1.
Retention times (min) of the PAHs, transitions (the quantitative ion is marked in bold) and
collision energy (V).
Analyte
Retention time (min)
MRMs
Collision Energy (V)
Naphthalene
5.5
128 > 128
128 > 102
10
30
Anthracene
11.8
178 > 178
178 > 152
10
30
Fluoranthene
18.2
202 > 202
202 > 200
10
30
Benzo [b] fluoranthene
36.5
252 > 252
252 > 250
10
30
Benzo [k] fluoranthene
37.1
252 > 252
252 > 250
10
30
Benzo [a] pyrene
38.2
252 > 252
252 > 250
10
30
Indeno [1,2,3-cd] pyrene
43.9
276 > 276
276 > 274
10
30
Benzo [g,h,i] perylene
45.5
276 > 276
276 > 274
10
30
