Recently, the Chinese govt announced that they will phase out the use and manufacture of the highly poisonous herbicide paraquat and the govt will cancel the registration and production license for paraquat by July 1, 2014. According to the facts about paraquat page on the US CDC site, ingestion of small to medium amounts of paraquat can result in liver, kidney, or heart failure plus scarring to the lungs. Research has also shown is being linked to the development of Parkinson’s disease. The EU banned paraquat in 2007, and many other countries, such as Malaysia have banned paraquat with now China following suit.
Paraquat mixed with diquat was used for a long time around the world to control crop and aquatic weeds. High-performance liquid chromatography (HPLC) is one commonly used method for the determination of diquat and paraquat. The U.S. Environmental Protection Agency (EPA) has published EPA Method 549.2 (downloadable PDF), a method for the determination of these herbicides in aqueous samples by liquid-solid extraction and high performance liquid chromatography (HPLC) with ultraviolet detection.
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Here, we present Application Brief 114, Improved Separation of Diquat and Paraquat Using the Acclaim Mixed-Mode HILIC-1 Column, (downloadable PDF) describing an efficient method for the baseline separation of diquat and paraquat with improved peak shape. The experiment was performed using a3 μm LC column that combines Reversed-Phase and Hydrophilic Interaction Phases (Thermo Scientific Acclaim Mixed-Mode HILIC-1 column) and our rapid separation liquid chromatography (RSLC) system (Thermo Scientific Dionex UltiMate 3000 RSLC system). Note that the separation of diquat and paraquat is difficult due to their very weak retention on a conventional reversed-phase C18 column; therefore, ion-pairing reagents are added to the mobile phase. These reagents are also added to improve peak shape.
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