A Simple Colorimetric Determination of Diquat and Paraquat Utilizing Automatic Reduction Property

Abstract

We developed a simple colorimetric method which can separately determine paraquat and diquat utilizing automatic reduction property of diquat under existence of tetramethylammonium hydroxide. In theˆrst step, diquat in the sample was automatically reduced by adding tetramethylammonium hydroxide, and UV/VIS spectrum (l max ＝430 nm) and absorbance at 430 nm were measured for conˆrma-tion and determination of diquat. In the second step, paraquat in the sample was also reduced by adding sodium hydrosulˆte, and UV/VIS spectrum (l max ＝396 nm, 600 nm.) and absorbance at 600 nm were measured for conˆrmation and determination of paraquat. The calibration curves were linear in the concentration range from 1 100 ppm for both compounds. The herbicide containing both paraquat and diquat, Preeglox L , showed typical UV/VIS spectra of each compound, and there was a good correlation between herbicide concentration and paraquat and diquat concentrations. The established method was successfully applied to forensic samples, gastric content and heeltap solution.

In vitro removal of paraquat and diquat from aqueous media using raw and calcined basil seed

“…The commercial product (7% diquat dibromide þ5% paraquat dichloride) was obtained from Syngenta Co., Ltd., Japan. Concentrations of paraquat and diquat were measured using previously reported methods (Nishida et al, 2005). Moreover, we confirmed that there was no change in the maximum absorption wavelength before and after the adsorption treatment in a preliminary experiment (the maximum absorption wavelengths of paraquat and diquat are 603 and 432 nm, respectively).…”