Methods for Sample Preparation and Analysis of Residual Levels of Selected Herbicides at Various Production Stages of Sugar from Industries in Ethiopia, Based on Literature Review
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Date
2006-07
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Addis Ababa Universty
Abstract
Sampling, sample preparation and analysis methods based on supported liquid membrane
atrazine and ametryn and phenoxyacid herbicides; 2,4-D. In SLM extraction, neutral
herbicides could be extracted from a flowing aqueous solution to a stagnant acidic
acceptor solution for the two weakly basic s-triazines and to stagnant basic acceptor
solution for the weakly acidic phenoxyacid herbicide. Specifically, a liquid membrane
containing 0.1 mol/L sulphuric acid for the triazines and 0.1 mol/L sodium hydroxide for
the 2,4-D was suggested. The uncharged herbicide molecules from the flowing aqueous
donor solution diffused through a liquid membrane impregnated in a porous
poly(tetrafluoroethylene) membrane, immobilized organic solvent, and then will be
trapped in a stagnant acceptor phase. The efficiency of the extraction process will be
found to depend on the donor solution pH, the amount of the mobile carrier added to the
liquid membrane and the concentration of the counter ion in the acceptor solution. From detailed studies, the optimum values of these parameters for the efficient extraction of the
herbicides will be determined. The applicability of the method for (SLM) have been
proposed for selective extraction of two s-triazine herbicides, namely extraction of these
selected herbicides at different stages of production of sugar will be also investigated by
spiking analyte sample solutions in sugar-cane juice, syrups, and molasses and sugar
crystal samples. The suggested method will be utilized for trace enrichment of the
analytes from samples containing matrices of various types and concentrations. A 20
minutes of sample enrichment at a flow rate of 1.0 mL/min, was suggested to determine
the concentrations of atrazine, ametryn and 2,4-D in sugar samples at various stages of
production.
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Keywords
Sample Preparation and Analysis Methods