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Batch square-wave voltammetric and flow-injection amperometric determination of trace amounts of bromofenoxim

✍ Scribed by Xiaohua Cai; Božidar Ogorevc; Emilio Benfenati; Kurt Kalcher; Milko Novič; Irena Grabec


Book ID
102982542
Publisher
Elsevier Science
Year
1995
Tongue
English
Weight
758 KB
Volume
310
Category
Article
ISSN
0003-2670

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✦ Synopsis


Two sensitive and rapid methods, batch voltammetric and flow-injection analysis (FIA) with amperometric detection are reported, for trace determination of the herbicide bromofenoxim. Preliminary results on its electrochemical behaviour are presented as well. While bromofenoxim did not exhibit any response at bare solid electrodes, two well-defined voltammetric reduction peaks were obtained at mercury electrodes. Both peaks, with peak potentials at -0.38 V and -0.54 V vs. Ag/AgCl in pH 7 Britton-Robinson buffer, appear as a consequence of a reduction of the two nitro groups of bromofenoxim, and show strong adsorption nature. The first peak, at the less negative potential, was found to be more sensitive and was therefore utilised for the voltammetric determination of bromofenoxim. In direct batch voltammetric analysis at a dropping mercury electrode by applying square-wave voltammetry @WV), linearity between SWV signal and bromofenoxim concentration was found to exist from OS kg/l to 600 pg/l (1.1 X lo-' mol/l to 1.3 X 10m6 mol/l), with an estimated limit of detection of 0.1 pg/l. Dynamic properties and in situ formation of the mercury film coated glassy carbon electrodes were also investigated for the determination of bromofenoxim in flow-injection systems. Employing FIA with amperometric detection at an operating potential of -0.7 V vs. Ag/AgCl, the signal response was linearly dependent on the bromofenoxim concentration within the range from 50 pg/l to 4000 pg/l (1.1 X 10e7 mol/l to 0.9 X 10K5 mol/l) and a detection limit (30) of 10 pg/l (0.4 ng absolute, 40 ~1) was obtained. Optimisation of parameters for the amperometric detection of bromofenoxim and utilisation of the proposed methods are presented and discussed.


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