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C
HANG
ET AL
.:
J
OURNAL OF
AOAC I
NTERNATIONAL
V
OL
.
99, N
O
.
4, 2016
1055
the deviation ratio accurately, the deviation ratio ranges of the
pesticides were recalculated without the interval data of day 80
(
see
Table 5).
Among the above-mentioned remaining 14 pesticides,
the deviation ratios were <15 , with most <10 , except
for pirimicarb and bromophos-ethyl, which had the highest
deviation ratios of 17.1 and 16.8 , respectively, and quinoxyfen
and benalaxyl, which had the lowest deviation ratios of í24.3
and í16.0 , respectively. It is evident that the proposed method
for predicting the residue concentrations of pesticides in aged
Oolong tea in this study is accurate.
The initial values of pesticides at
c
and
d
concns, together
with their deviation ratios, are also listed in Table 5. It can
be seen that the six pesticides with relatively higher deviation
Table 2. Degradation equations of 20 representative pesticides in aged Oolong tea at
c
and
d
concns over 90 days by
GC-MS/MS
a
No.
Pesticide
c
Concn
d
Concn
Initial value (TXDWLRQ RYHU
GD\V
R
2
Initial value (TXDWLRQ RYHU
GD\V
R
2
1
7ULÀXUDOLQ
214.4
\ í OQ [
0.548
248.6
\ í OQ [
0.787
2
7HÀXWKULQ
106.1
\ í OQ [
0.742
122.6
\ í OQ [
0.832
3
Pyrimethanil
116.9
\ í OQ [
0.693
124.7
\ í OQ [
0.77
4
Propyzamide
119.6
\ í OQ [
0.512
126.6
\ í OQ [
0.598
5
Pirimicarb
114.7
\ í OQ [
0.822
126.2
\ í OQ [
0.873
6
Dimethenamid
46.2
\ í OQ [
0.702
51.9
\ í OQ [
0.86
7
Fenchlorphos
240.3
\ í OQ [
0.533
267.4
\ í OQ [
0.785
8
Tolclofos-methyl
116.7
\ í OQ [
0.543
130.5
\ í OQ [
0.78
9
Pirimiphos-methyl
113.0
\ í OQ [
0.74
126.3
\ í OQ [
0.867
10
ƍ ''(
451.7
\ í OQ [
0.794
466.9
\ í OQ [
0.824
11
Bromophos-ethyl
116.0
\ í OQ [
0.686
124.2
\ í OQ [
0.784
12
ƍ ''(
451.7
\ í OQ [
0.768
466.9
\ í OQ [
0.805
13
Procymidone
117.9
\ í OQ [
0.587
120.3
\ í OQ [
0.733
14
Picoxystrobin
234.0
\ í OQ [
0.717
236.0
\ í OQ [
0.774
15
Quinoxyfen
115.9
\ í OQ [
0.667
116.4
\ í OQ [
0.653
16
Chlorfenapyr
965.0
\ í OQ [
0.579
966.0
\ í OQ [
0.65
17
Benalaxyl
116.8
\ í OQ [
0.763
118.9
\ í OQ [
0.746
18
Bifenthrin
112.9
\ í OQ [
0.653
114.8
\ í OQ [
0.728
19
'LÀXIHQLFDQ
118.6
\ í OQ [
0.571
119.4
\ í OQ [
0.576
20
Bromopropylate
237.4
\ í OQ [
0.524
240.0
\ í OQ [
0.647
a
7KH GHJUDGDWLRQ HTXDWLRQV ZHUH REWDLQHG E\ SORWWLQJ GHWHUPLQDWLRQ WLPH HYHU\ GD\V RQ WKH
x
-axis and concentration on the
y
-axis.
Figure 10. Logarithmic chart of dimethenamid in aged Oolong
tea. The determination times (days) were plotted on the
x
-axis, and
WKH GLIIHUHQFHV EHWZHHQ HDFK PHDVXUHG YDOXH DQG WKH ¿UVW WLPH
measured value (degradation value) of target pesticides were
plotted on the
y
-axis.
Table 3. Logarithmic functions of 20 pesticides in aged
Oolong tea at
d
concn
a
No.
Pesticide
Logarithmic function
R
2
1
7ULÀXUDOLQ
\ OQ [
0.705
2
7HÀXWKULQ
\ OQ [
0.641
3
Pyrimethanil
\ OQ [ í
0.758
4
Propyzamide
\ OQ [ í
0.620
5
Pirimicarb
\ OQ [ í
0.800
6
Dimethenamid
\ OQ [ í
0.807
7
Fenchlorphos
\ OQ [ í
0.768
8
Tolclofos-methyl
\ OQ [
0.698
9
Pirimiphos-methyl
\ OQ [ í
0.781
10
ƍ ''(
\ OQ [ í
0.748
11 Bromophos-ethyl
\ OQ [ í
0.757
12
ƍ ''(
\ OQ [ í
0.705
13
Procymidone
\ OQ [ í
0.600
14
Picoxystrobin
\ OQ [ í
0.740
15
Quinoxyfen
\ OQ [ í
0.744
16
Chlorfenapyr
\ OQ [ í
0.630
17
Benalaxyl
\ OQ [ í
0.722
18
Bifenthrin
\ OQ [ í
0.761
19
'LÀXIHQLFDQ
\ OQ [ í
0.730
20 Bromopropylate
\ OQ [ í
0.596
a
'HWHUPLQDWLRQ WLPH GD\ ZDV SORWWHG RQ WKH
x
-axis and the difference
EHWZHHQ HDFK PHDVXUHG YDOXH DQG WKH ¿UVW WLPH PHDVXUHG YDOXH
GHJUDGDWLRQ YDOXH RI WKH WDUJHW SHVWLFLGHV ZDV SORWWHG RQ WKH
y
-axis,
DQG WKHQ WKH ORJDULWKPLF IXQFWLRQV ZHUH ¿WWHG