Published:Journal of Chromatographic Science,
ISSN 0021-9665 Volume
46, Number 8, September 2008, pp. 751-756
Determination of Metolcarb and Diethofencarb
in Apples and Apple Juice by Solid-Phase Microextraction–High
Performance Liquid Chromatography
Xiu-Min Yang1, Ou Wang2,
Ming-Zhao Wang2, Yan-Xue
Hu2, Wei-Ning Li, and Zhi Wang1
Key Laboratory of Bioinorganic Chemistry, College of Science,
Agricultural University of Hebei, Baoding 071001, China and 2College
of Food Science and Technology, Agricultural Iniversity of Hebei,
Baoding 071001, China
A method for the determination of metolcarb and
diethofencarb in apples and apple juice is developed using solid-phase
microextraction (SPME) coupled with high-performance liquid chromatography
(HPLC). The experimental conditions of SPME, such as the kind
of extraction fiber, extraction time, stirring rate, pH of the
extracting solution, and desorption conditions are optimized.
The SPME is performed on a 60 µm polydimethylsiloxane/divinylbenzene
fiber for 40 min at room temperature with the solution being
stirred at 1100 rpm. The extracted pesticides on the SPME fiber
are desorbed in the mobile phase into SPME–HPLC interface
for HPLC analysis. Separations are carried out on a Baseline
C18 column (4.6 i.d. × 250 mm, 5.0 µm) with acetonitrile–water
(55/45, v/v) as the mobile phase at a flow rate of 1.0 mL/min,
and photodiode-array detection at 210 nm. For apple samples,
the method is linear for both metolcarb and diethofencarb in
the range of 0.05–1.0 mg/kg (r > 0.99), with
a detection limit (S/N = 3 ) of 15 and 5 µg/kg, respectively.
For apple juice, the method is linear for both metholcarb and
diethofencarb over the range of 0.05–1.0 mg/L (r > 0.99)
with the detection limit (S/N = 3 ) of 15 and 3 µg/L, respectively.
Excellent recovery and reproducibility values are achieved. The
proposed method is shown to be simple, sensitive, and organic
solvent-free, and is suitable for the determination of the two
pesticides in apples and apple juice.
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