Agriculture Reference
In-Depth Information
Figure 5.2.
GPC chromatogram of a standard fortified sample.
(4
+
1, v/v), acetonitrile, and acetonitrile with 1% acetic acid (v/v)
—
are selected to
compare their extraction ef
ciencies
for 77 representative environmental
pollutants.
For each solvent, three standard added samples and one matrix standard are
prepared for calculating recoveries of 77 environmental pollutants. The results of
three standard added samples are averaged before the calculation of recoveries.
Accurately weigh 5 g fat sample, add standard solution of 2 LOQ (a S/N ratio of
>
10 is the criterion for LOD in the research; see Table 5.4) and 35ml extraction
solvent, the extraction method is homogeneous extraction, and repeat twice. After
concentration and GPC cleanup, GC
-
MS/MS is used to detect the analytes, and
internal standard is used for quanti
cation. The results of comparison are shown in
Figure 5.3.
On comparing the recoveries of seven solvents for 77 environmental pollutants,
it is found that the recoveries obtained with acetonitrile, ethyl acetate
-
cyclohexane
1,
v/v) are similar and these solvents are suitable, but the recovery with acetonitrile
with 1% acetic acid is the worst. On comparing the RSDs, it is found that
acetonitrile is the best, and acetonitrile with 1% acetic acid is the worst. Thus,
these environmental pollutants are unsuitable to be extracted in acidic conditions.
Furthermore, the fat is not easily dissolved in acetonitrile, and the matrix in
(1
+
1, v/v),
n
-hexane
-
acetone (1
+
1, v/v), and
n
-hexane
-
dichloromethane (4
+
uence
by acetonitrile extraction is less than the in
uence by other solvent extractions, thus
facilitating the cleanup. Therefore, acetonitrile is selected as the extraction solvent
in this study.
