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Title: Analysis of phenoxy herbicides in bovine milk by means of liquid-liquid-liquid microextraction with a hollow-fiber membrane
Authors: Zhu, L.
Huey Ee, K.
Zhao, L.
Lee, H.K. 
Keywords: Extraction methods
Food analysis
Hollow-fiber membranes
Liquid-liquid-liquid microextracion
Membrane extraction
Phenoxy acids
Issue Date: 19-Jul-2002
Citation: Zhu, L., Huey Ee, K., Zhao, L., Lee, H.K. (2002-07-19). Analysis of phenoxy herbicides in bovine milk by means of liquid-liquid-liquid microextraction with a hollow-fiber membrane. Journal of Chromatography A 963 (1-2) : 335-343. ScholarBank@NUS Repository.
Abstract: A preconcentration technique, which involves liquid-liquid-liquid microextraction, was developed to determine phenoxy herbicides in bovine milk. A layer of organic phase was impregnated into the pores of a 3.5 cm long porous hollow fiber, while the internal volume of the fiber was filled with NaOH solution (the acceptor solution) that was connected directly to the needle of a microsyringe. The fiber was then immersed into 8 ml of acidified milk sample. When the sample solution was stirred, acidic analytes were extracted into the organic phase and back extracted simultaneously into the alkaline acceptor medium as the analytes were protonated at low pH and deprotonated at high pH. After extracting for a prescribed time, 5 μl acceptor solution was taken back into the syringe and injected directly into a HPLC system for quantification. The analytes were extracted quantitatively from the sample solution into the acceptor solution with a large enrichment factor of 900. Due to its low cost, the hollow-fiber extraction device was disposed of after a single extraction that eliminated the possibility of carry over effects. In addition, because a small volume of organic solvent was required and little waste is generated, the procedure is environmentally friendly, and is compatible with the "green chemistry" concept. © 2002 Elsevier Science B.V. All rights reserved.
Source Title: Journal of Chromatography A
ISSN: 00219673
DOI: 10.1016/S0021-9673(02)00138-3
Appears in Collections:Staff Publications

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