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臺灣農藥科學 第
1
期
ing potential [DP] of 40 V, an entrance poten-
tial [EP] of 10 V, collision energy [CE] of 29
eV, and a collision cell exit potential [CXP] of
10 V) and 171/71 (DP of 86 V, EP of 10 V, CE
of 55 eV, and CXP of 14 V), were selected and
used as the quantitative transition and qualita-
tive transition, respectively.
Results and Discussion
To evaluate the validity of our proposed
method, five replicate recovery studies were
performed on adzuki beans at three fortifica-
tion levels: low (0.05 mg/kg), medium (0.20
mg/kg), and high (0.50 mg/kg). Intraday re-
peatability was verified over three days. On
each of these days, five fortified samples were
analyzed. Interday repeatability was verified by
analyzing five fortified samples on three dif-
ferent days. Recovery levels were calculated by
comparing the peak areas of fortified samples
with those of matrix matched calibration stan-
dards. Intraday and interday recovery levels are
shown in Table 1. Under low fortification (0.05
mg/kg), the intraday recoveries of paraquat
were 74.5%, 72.5%, and 90.7% with relative
standard deviations (RSDs) of 10.9%, 4.4%,
and 12.6%, respectively. Considering intraday
recoveries under medium (0.20 mg/kg) and
high (0.50 mg/kg) fortification, our method
also yielded acceptable recovery values, ranging
from 63.3% to 98.3%, with RSDs within 11.1%.
In addition, acceptable interday recoveries
were achieved, with RSDs within 17.1%. These
results indicate that our proposed method is
applicable for the determination of paraquat
in adzuki beans. Compared to the method
described by Zou et al.
(6)
, our method is more
streamlined as it does not require a column
clean-up step (i.e., solid phase extraction puri-
fication). Meanwhile, the limit of quantification
(LOQ) of our method (obtained by spiking
various levels of paraquat in adzuki beans) was
0.05 mg/kg (S/N = 112.7). In Taiwan, the maxi-
mum paraquat residue limit in dry beans, in-
cluding adzuki beans, is 0.2 mg/kg
(5)
. Therefore,
the method proposed in this report may satisfy
current regulatory needs in Taiwan.
Conclusion
In this study, we developed a novel meth-
od for the determination of paraquat residues
in aduzki beans. Our proposed method can be
performed using a rapid, simple, sensitive, and
efficient procedure and should be suitable for
the routine inspection of aduzki beans.
Table 1.
Recovery levels of paraquat in adzuki beans
Fortification level
Intraday recovery (n = 5)
Interday recovery
1
2
3
Mean
(%)
RSD
1)
(%)
Mean
(%)
RSD
1)
(%)
Mean
(%)
RSD
1)
(%)
Mean
(%)
RSD
1)
(%)
Low (0.05 mg/kg)
74.5
10.9
72.5
4.4
90.7
9.0
79.2
12.6
Medium (0.20 mg/kg)
98.3
3.0
70.6
8.7
79.3
4.6
82.8
17.1
High (0.50 mg/kg)
72.1
11.1
63.3
5.0
68.4
8.1
68.0
6.5
1)
RSD: relative standard deviation.