Determination of methylviologen (Paraquat) by differential pulse polarography |
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Authors: | P Yáñez-Sedeño J M Pingarrón L M Polo Díez |
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Institution: | (1) Department of Analytical Chemistry, Faculty of Chemistry, Complutense University of Madrid, Madrid, Spain |
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Abstract: | Summary
Determination of Methylviologen (Paraquat) by Differential Pulse Polarography
The second reduction wave of methylviologen ( Paraquat ) has been studied at pH 2 by different polarographic techniques. The limiting current is diffusion-controlled. Evidence for dimerization of the radical formed in the first reduction step has been obtained. The n values for the reduction process have been calculated at concentration levels where the dimer and the monomer predominate. Paraquat can be determined by differential pulse polarography in the 6.0×10–5–4.0×10–7
M concentration range, the limit of determination being 1.7×10–7
M. The method has been applied to paraquat determination in commercial herbicides. |
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