Fluorescence Detecting of Paraquat and Diquat Using Host-Guest Chemistry with a Fluorophore-Pendant Calix[6]arene

Paraquat (PQ) and diquat (DQ), some of the most widely used herbicides in the world, bothpresent a high mortality index after intentional exposure. In this paper, a fluorescence sensing methodfor PQ and DQ, based on host-guest molecular recognition, is proposed. Calix[6]arene derivativescontaining anthracene or naphthalene as pendant fluorophore at their lower rim recognize DQ andPQ in hydroalcoholic solution with a broad linear response range at the g L?1 level concentration.The linear response ranges were found from 1.0 to 18 g L?1 with the detection limit of 31 ng L?1for paraquat, and from 1.0 to 44 g L?1 with the detection limit of 0.16 g L?1 for diquat. Therecognition process is detected by following the decrease in the fluorescence emission consequent tocomplexation. The proposed quenching method has been applied to the determination of paraquatin drinking water samples.