HPLC Analysis of Paraquat and Diquat on Zodiac HST TH Column

Paraquat and diquat are two of the most widely used herbicides globally, both known for their toxicity to humans and animals. Their presence in water sources is strictly regulated by the EPA. Structurally similar, both compounds contain two quaternary amine groups, making them highly polar and strongly basic, which poses a challenge for traditional reversed-phase chromatography due to poor retention and peak shape caused by residual silanol interactions.

The Zodiac HST TH mixed-mode column enables effective retention and separation of paraquat and diquat with excellent peak shape and without the need for ion-pairing reagents. This method is suitable for analyzing these herbicides in a variety of matrices, including soil, groundwater, and drinking water, and offers a robust, LC/MS-compatible solution for simultaneous analysis in a single run.