Short communicationAnalysis of flufenacet in soil, wheat grain and straw by gas chromatography
Introduction
Flufenacet (Foe 5043) {N-(4-fluorophenyl)-N-(1-methyl-ethyl)-2-[5-(trifuoromethyl)-1,3,4-thiadiazol-2-yl]oxy]acetamide}, a new soil acting herbicide has been introduced recently as a selective herbicide to control grassy weeds in a wide range of crops including cereals [1], [2].
Although there are several reports on the efficacy of flufenacet against various weeds in cereal crops, there are very few reports on the method of analysis and its environmental fate in agro ecosystems. Gould et al., (1997) reported a gas chromatography–selected ion monitoring–mass spectroscopy (GC–MS–SIM) for measuring residues of Foe 5043 and its metabolites in different crops [3]. In this method the residues were briefly oxidized and hydrolyzed to the corresponding fluoroaniline by digesting the crop matrix with sulfuric acid. The fluoroaniline was separated from fortified crop matrix by steam distillation, recovered by extraction and derivatized. The derivative was measured by GC–MS–SIM. The method gave recoveries of 67–116% of Foe 5043 and its metabolites at the 0.10 ppm level. The environmental fate of flufenacet in soil under anaerobic and aerobic conditions was studied using labeled [phenyl-U-14C]Foe 5043. It was relatively stable under anaerobic compared to aerobic conditions [4].The half-life of flufenacet ranged between 33 and 64 days under aerobic conditions [5]. The method described in this paper presents a sensitive and simple procedure for measuring of flufenacet residue in soil as well as wheat grain and straw.
Section snippets
Chemicals
The analytical-grade flufenacet (99.6% purity) was supplied by M/S Bayer India Ltd. All solvents were distilled before use.
Preparation of standards
A stock solution of flufenacet (1000 μg ml−1) was prepared by dissolving 25 mg of analytical-grade herbicide in 25 ml of acetone. Other flufenacet solutions (1, 0.5, 0.1, 0.05, 0.01 μg ml−1) were prepared from the stock solution by dilution with hexane.
Instrument
The method employed a Hewlet–Packard gas chromatograph, model HP 5890, equipped with a 63Ni electron-capture detector, a 10
Results and discussion
Flufenacet was resolved as a single peak by GC and had a retention time (Rt) of 2.07 min (Fig. 1A). The method showed linearity over a range from 0.01 to 1.0 μg ml−1 (Table 1). The limit of determination of the technique was 0.03 ng of flufenacet.
Three-fold injections of flufenacet (0.01 to 1 μg ml−1) were used to determine the standard deviation. It was observed that triplicate injections of each sample were optimum for operating in a 95% confidence interval. It was found that limit of
Acknowledgements
The authors are grateful to M/S Bayer India Ltd. for supplying analytical grade herbicide and Dr (Mrs.) Sashi Bala Singh and Ms. Nirmali Saikia for the analytical help rendered.
References (5)
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(1998)