A highly sensitive fluorescence probe for methyl parathion detection in vegetable and fruit samples based on N and S co-doped carbon dots

In this work, a highly sensitive fluorescence sensing system based on nitrogen and sulphur co-doped carbon dots (N,S-CDs) was for the first time developed for indirect measurement of methyl parathion (MP) with the aid of alkaline-induced hydrolysis. The N,S-CDs were prepared by using o-phenylenediamine and l-cysteine as precursors via hydrothermal heating. In a strong alkaline environment, MP was hydrolysed to p-NP which can suppress the fluorescence of N,S-CDs via a combination of IFE and dynamic interaction. The N,S-CDs exhibited high selectivity and sensitivity towards MP sensing, achieving a linear range of 0.01–15.0 μg/mL and a detection limit as low as 1.56 ng/mL. The proposed sensing platform was applied for MP detection in vegetable and fruit samples with satisfactory results. The recoveries were in a range of 96.4–104.4 %, and the relative standard deviations (RSDs) were less than 3.02 %.