Influence of organic matter and surfactants on solid-phase extraction of diquat, paraquat and difenzoquat from waters

Different Approaches for Paraquat Quantification in Waters

“…The limits of detection and quantification were calculated based on a signal-tonoise ratio (S/N) of 3 and 10 and are 0.04 and 0.1 µg/L, respectively. The LOD of 0.04 µg/L of PQ is of the same order of magnitude [28,30,31,33] or lower [27,29,37] than the values reported in other studies of the literature.…”

“…Silica was chosen because it is one of the most polar sorbents available for SPE and proved to be a valid option for analysis of quaternary ammonium (QA) compounds like PQ [24][25][26][27][28][29][30][31] . The Oasis WCX sorbent, which is a polymeric reversed-phase, weak ion exchange mixed-mode sorbent, was also considered because it was designed for highly selective sample preparation of strong basic compounds and quaternary amines.…”

“…In particular, hydrochloric acid has been used as eluent in SPE pre-concentration procedures for PQ in waters [25,26,29] . Methanol (MeOH) was tested because it is sometimes applied in some eluents to desorb PQ from a wide range of SPE sorbents: silica [25][26][27][28][29][30][31] , graphitized carbon black [33] , resin [34] , alumina [35] . On the other hand, MeOH has lower boiling point than water and so, the pre-concentration step of the final extract by solvent evaporation is facilitated.…”

“…On the other hand, MeOH has lower boiling point than water and so, the pre-concentration step of the final extract by solvent evaporation is facilitated. Ammonium compounds such as ammonium sulphate [27,28,31,33] , ammonium chloride [34] , ammonium formate [36] and ammonium hydroxide [37] have been widely used to elute PQ in SPE. Saturated ammonium chloride is often used as PQ displacement agent in other matrices such as soils [38,39] .…”

Photochemical changes and oxidative damage in the aquatic macrophyte Cymodocea nodosa exposed to paraquat-induced oxidative stress

“…Paraquat (Pq) is widely used around the world to prevent growth of broadleaf weeds and grasses and is reaching the aquatic environment by runoff or leaching [2]. It has been classified among the most toxic and hazardous herbicides with high water solubility and rapid uptake by plant leaves and is the third most widely used herbicide [3,4].…”