Page 50 - Volume 1, Issue 2, July 2008

Liapis et al. 102
pesticide residue analysis, to the GC/MS/
MS determination of PAHs in water. This
would allow determination of pesticides
as well as PAHs using one single extrac-
tion and thus reducing the sample prep-
aration time.
Performance of the method was eval-
uated by determining the basic valida-
tion parameters, i.e. accuracy, precision
and sensitivity. The accuracy was assessed
from the attained recoveries, the precision
from the relative standard deviation (RSD)
values, and the sensitivity by estimating
the limits of quantification (LOQs).
The method did not provide satisfac-
tory resolution between benzo [b] fluoran-
thene and benzo [k] fluoranthene and for
this reason they were treated as one peak
in the calculation of the obtained recover-
ies (Figure 1). Since the maximum accept-
able limit set for these compounds is ex-
pressed as the sum of the four compounds
(benzo [b] fluoranthene, benzo [k] fluoran-
thene, indeno [1,2,3-cd] pyrene and benzo
[a] anthracene (3), actually there is no prob-
lem from the poor resolution of the two.
Recoveries (Table 2) for anthracene
were high, 146-160%, but with an accept-
able repeatability (relative standard devi-
ations ranged from 10.3 to 17.8%). For the
other PAHs, as shown in Table 2, the aver-
age recovery values were 50.7%-84% in
the lower level of fortification (0.05 μg/l),
58.4-81.7% in the second fortification lev-
Figure 1. Chromatogram of a fortified water sample at
0.05μg/L with (1) naphthalene, (2) anthracene, (3) fluoran-
thene, (4) benzo [b] fluoranthene, (5) benzo [k] fluoranthene,
(6) benzo [a] pyrene, (7) indeno [1,2,3-cd] pyrene and (8) ben-
zo [g,h,i] perylene.
Table 2. Mean recoveries (%) and relative standard deviation values (RSD, %) after fortification of
water samples in 3 fortification levels with 6 replicates/level.
Compound
1st level (n=6) 2nd level (n=6) 3rd level (n=6)
C (μg/l)
Recovery (%)
RSD (%) C (μg/l)
Recovery (%)
RSD (%) C (μg/l)
Recovery (%)
RSD (%)
Naphthalene 0.05 84 9.8 0.1 81.7 12.1 0.2 86 13.7
Anthracene 0.05 146 13.5 0.1 160 10.3 0.2 148 17.8
Fluoranthene 0.05 82.4 11.8 0.1 80.1 13.6 0.2 80.6 12.4
Benzo [b] fluoranthene 0.05 0.1 0.2
Benzo [k] fluoranthene 0.05 62.1 7.9 0.1 73.6 13.6 0.2 51.9 20.2
Benzo [a] pyrene 0.05 58.4 16.8 0.1 59.4 14.9 0.2 52.4 21.8
Indeno [1,2,3-cd] pyrene 0.05 61.7 18.6 0.1 58.4 16.8 0.2 60.7 23.4
Benzo [g,h,i] perylene 0.05 50.7 18.4 0.1 67.8 15.5 0.2 52.94 14.5