Determination of Abamectin Residue in Paprika by High ...

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Wen-Ming Xie, Kwang-Yong Ko, Sung-Hun Kim, Hee-Ra Chang, and Kyu-Seung Lee
control samples to assess the analytical method proposed
for AVMs residues. Prior to extraction, the series
of the control samples were fortified with AVMs standard
solution in acetonitrile at specified concentrations
according to the MRL in pepper and linear range.
After standing for 2 hours, the analytical procedures
mentioned above were carried out to produce recovery
data.
Method evaluation
B 1a
RESULTS AND DISCUSSION
AVMs and the degradation compound 8, 9-Z-AVM
were determined in paprika using the HPLC
method with fluorescence detector. The Fig. 2 shows
the UV absorption spectra of AVM B 1a and fluorescence
spectra of AVM B 1a derivative. The absorbance spectra
were shown to exhibit absorbance maxima at 244 nm
for AVMs and 242 nm for 8, 9-Z-AVM B 1a. According
to the excitation and emission spectra of AVM, 365
nm and 470 nm were chosen as excitation and emission
wavelength to get the highest detection sensitivity.
The RP-HPLC system used for this method provided
an excellent separation for all three compounds
showing baseline separation. The representative chromatograms
of a mixture of these three compounds and
their derivatives are shown in Fig.3. The derivative
formation was instantaneous 17) . When the aged reagents
were used, the yield was decreased and an extra peak
appeared 6) . Using acetonitrile-water (96:4, v/v) as mobile
phase, derivatives eluted after 8.0 and 9.7 minutes
and no interference was found in paprika extracts.
The standard curves for these AVM B 1a+8, 9-AVM
B 1a and AVM B 1b exhibited excellent linearity over the
following concentration ranges: AVM B 1a+8, 9-AVM
B 1a, 11.97-1197 ng/mL, AVM B 1b, 1-96.6 ng/mL. The
linear ranges were selected on the basis of expected
residue concentration and the MRL of ABM in paprika.
The linear correlation coefficients of calibration
curves for AVM B 1a+8, 9-Z-AVM B 1a and AVM B 1b
were 0.999 and 0.998, respectively.
Paprika samples spiked at two levels (20 and 200
μg/kg) of ABM were analyzed three times using the
prescribed procedure for extraction, clean-up and derivatization.
The results, summarized in Table 1, indicate
that the recoveries, ranged from 93% to 115%, and the
repeatability, less than 10% ,was satisfactory for trace
residue analysis.
The lowest level of quantitation for AVMs in paprika
was calculated as 2 μg/kg for AVM B1a, including
8,9-Z-AVM B 1a ,with a 5 g spiking sample portion.
Considering the MRLs of AVMs in most vegetables,
range from 10 to 50
μg/kg, the sensitivity was high
enough for routine residue analysis of fruit and vegetable
samples.
Terminal residue of AVMs in the field experiment
ABM has been linked to a wide spectrum of human
health hazards, ranging from short-term impacts to
chronic impacts. Chronic health effects may occur years
mV
0 100 200 300 400
A
8 . 083
B
9.708
Standard
Sample
B lank
0 2 4 6 8 10 12 14
Minute
Fig. 2. UV absorption spectra of avermectin (AVM) and
Fig. 3. Chromatograms of AVM derivatives in standard
fluorescence spectra of AVM derivative.
and sample extract. A: AVM B 1b, , B: AVM B 1a+8, 9-Z-
A: UV absorption spectrum of AVM B1. B and C: excitation
AVM B 1a.
and emission spectrum of AVM B1 derivative HPLC conditions: RP Symmetry C 18 stainless column (3.9
mm i.d.×150mm, Waters Associates). The mobile phase,
consisting of water in acetonitrile (4+96, v/v), was pumped
at the total flow of 1.2 mL/min