A novel fluorescence probing strategy for the determination of parathion-methyl.

Abstract A sensitive fluorescence probing strategy for parathion-methyl (PM) detection was developed based on electron transfer (ET) between p -nitrophenol (the hydrolysate of PM) and CdTe quantum dots (QDs) in cetyltrimethylammonium bromide (CTAB). PM was hydrolyzed by organophosphorus hydrolase (OPH) to form p -nitrophenol. P -nitrophenol is a typically electron-deficient compound due to the strong electron-withdrawing effect of the nitro groups. The positive charge of CTAB which make it assemble with electronegative mercaptopropionic acid-capped QDs, could be used as an absorbent for p -nitrophenol due to the strong hydrophobic interaction between the long alkyl chain of CTAB and aromatic ring of p -nitrophenol. Thus, the fluorescence intensity of CdTe QDs/CTAB probe could be quenched by p -nitrophenol due to the ET mechanism. The fluorescence intensity of the QD/CTAB system was proportional to PM concentration in the range of 25–3000 ng mL −1 , with a detection limit of 18 ng mL −1 . Furthermore, the proposed method was simple in design and fast in operation, and has been successfully used for PM detection in environmental and agricultural samples with satisfactory recovery.