Joint International Conference on Long-term Experiments ...

Table 2: Determination results for test L1
Fat content %
Methods
Reference
method
AOAC
Column
extraction
Partition
extraction
Determination 1 4.02 3.87 3.99 4.04
Determination 2 4.22 4.08 4.15 4.28
Determination 3 4.15 3.93 4.12 4.33
Nr 3 3 3 3
Average 4.130 3.960 4.087 4.217
Standard deviation 0.101 0.108 0.085 0.155
t 1.9913 0.5642 -0.8155
Table 3: Determination results for test L2
Fat content %
Methods
Reference
method
AOAC
Column
extraction
Partition
extraction
Determination 1 3.9 3.73 3.81 4.02
Determination 2 3.85 3.62 3.98 4.09
Determination 3 4.07 3.89 4.12 4.15
Nr 3 3 3 3
Average 3.940 3.747 3.970 4.087
Standard deviation 0.115 0.136 0.155 0.065
t 1.8414 -0.2692 -1.9274
The statistic analysis was performed through the t – student test (Ardelean M. 2005) and
it shows the fact that the differences are not significant between the reference method
and the three applied methods, which are used for pesticide separation with fat in milk
tests that are supposed to be contaminated.
However the AOAC method values are the most far away from the reference one
and the “t” value for 4 degrees of freedom are very close to the value that make the
distinction from un-significant values to significant values. But, since we worked at this
case on a reduced scale, as shown from the description of the work methods, it is
possible that the deviation is influenced by this aspect.
However, the extraction method and the partition method have results very close to
one another in respect to the reference method and can be used for the fat separation in
the case of pesticides determination from milk tests, which can be seen in the graphics
from figure 1 and 2. Later, the separated fraction is submitted to qualitative and
quantitative purification and determination through instrumental methods.
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