Chemistry Reference
In-Depth Information
recovery spiked at 0.5 mg/kg was between 68-85% but difenoconazole recovery was very
high at 151%. Contrary to the recovery spiked at 0.05 mg/kg, recoveries spiked at 1 mg/kg
were very high (more than 100%) for most compounds between 86-142% and CV for all
compounds did not meet the range. The overall average recovery was 90.7% for all
fortification levels.
Carrot
1.0 mg kg
-1
0.5 mg kg
-1
1.0 mg kg
-1
Triadimenol
86.0 (15.2)
69.8 (7.4)
48.3 (6.1)
Cyproconazole
113.0 (14.2)
72.9(11.0)
64.7 (8.6)
Myclobutanil
126.0 (14.4)
75.3 (8.2)
54.7 (5.4)
Triadimefon
121.0 (18.8)
68.6 (8.2)
50.4 (10.8)
Tebuconazole
142.0 (15.5)
75.5 (7.3)
73.9 (46.7)
Fenbuconazole
109.0 (14.3)
74.4 (8.0)
51.0 (7.4)
Hexaconazole
115.0 (16.2)
85.5 (8.6)
66.5 (6.6)
Propiconazole
137.0 (14.9)
72.3 (7.1)
110.6 (56.6)
Difenoconazole
121.0 (15.8)
151.0 (6.8)
111.4 (6.1)
Table 5.
Recovery of Triazoles in carrot (n=5)
160
140
120
100
80
60
40
20
0
0.05mg/kg
0.5mg/kg
1mg/kg
Figure 9.
Recoveries fortified in Carrot (n=5 at each level)
4. Conclusion
Lower recoveries for some analytes in certain matrices and at certain concentrations in
pesticide residue analysis could be due to the degradation of base sensitive pesticides in
higher pH samples, or degradation of acid sensitive pesticides in lower pH samples. And
protonization of basic pesticides in acidic conditions reduces partition into organic layer.
For consistent and higher recoveries, some considerations that we need to look into are the
homogeneity of the samples, the choice of solvent, sorbent(s) and salt(s) used during clean-
up process. The EtOAc modified QuEChERS method was demonstrated to provide
