Page 44 - Volume 3, Issue 2, July 2010

© Benaki Phytopathological Institute
Pesticides in cereal-based baby foods 75
two different separation systems (two dif-
ferent columns) because they are not sensi-
tive to the NPD. For pesticides like cadusa-
fos, disulfoton, terbufos and others that
are sensitive to both detectors, confirma-
tion was achieved by two different columns.
Figure 1 shows a spiked cereal-based baby
food sample with fensulfothion and fensul-
fothion sulfone at 3 μg/l in various columns
and detectors.
Linearity
Calibration curves were constructed
from data acquired after injecting of ma-
trix-matched calibration standards in con-
trol matrix of cereal-based baby foods in
2,2,4-trimethylpentane/toluene (90/10) of
the 25 pesticides at eight concentration lev-
els, i.e. 3, 6, 8, 10, 15, 20, 30 and 40 μg/l. In
Table 2, the basic calibration line parameters
for the analytes are presented. Linearity pa-
rameter values were found acceptable for
most pesticides, with coefficients of deter-
mination (r2) higher than 0.98 in most cases.
However, some pesticides, such as ometh-
oate and terbufos sulfoxide, did not exhib-
it good linear behaviour, due to the fact that
they are polar compounds so they achieved
low sensitivity and poor chromatography at
the under study concentration range. Due
to the variability in the peak area resulting
from the use of the calibration curve, the ap-
propriate value C (mg/kg) was estimated by
the following equation:
where,
Figure 1. Chromatogram of spiked cereal-based baby food sample with fensulfothion and fensulfothion sulfone at 3 μg/kg
analyzed by (A) column DB-5MS, detector ECD, (B) column DB-17MS, detector ECD, (C) column DB-5MS, detector NPD, (D)
column DB-17MS, detector NPCD.