Published:Journal of Chromatographic Science,
ISSN 0021-9665Volume
40, Number 7, August 2002, pp. 387-391
Determination of Acidic Herbicides in Surface Water by Solid-Phase
Extraction Followed by Capillary Zone Electrophoresis
Weidong Qin[1], Hongping Wei[2], and Sam Fong Yau Li[1],[2]
[1]Department of Chemistry, National University of Singapore, 119260, Republic
of Singapore and
[2]CE Resources Pte. Ltd., NUS Innovation Center, 8 Prince George’s Park,
118407, Republic of Singapore
A rapid solid-phase extraction–capillary zone electrophoresis
(CZE) method for determining 2,4-dichlorophenoxyacetic acid, 4-(2,4-dichlorophenoxy)
butyric acid, and 2,4,5-trichlorophenoxyacetic acid in real water samples is
described. Factors affecting the recoveries and detection of the targets are
investigated. With samples being acidified to pH 2 and salted by sodium sulfate
to 2% (w/w), an average recovery of greater than 85% is obtained using ethyl
acetate as the eluent on an octadecylsilane-bonded silica cartridge. A running
buffer of 5mM sodium tetraborate in a water–acetonitrile mixture (70:30,
v/v) adjusted to pH 9 is employed in the CZE analysis, and the targets can be
analyzed within 7 min with good reproducibility and acceptable sensitivity.
The method is suitable for detecting herbicide residues of sub- parts-per-billion
levels in surface water. A local pond water is analyzed, and the concentrations
of 2,4-dichlorophenoxyacetic acid and 4-(2,4-dichlorophenoxy) butyric acid are
detected to be 0.27 ± 0.03 ppb and 0.61 ± 0.08 ppb, respectively.
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