Persistence, decontamination and dietary risk assessment of propyrisulfuron residue in natural paddy field environment using QuEChERS@UPLC-Q-TOF-MS/MS

A modified QuEChERS technology combined with UPLC-Q-TOF-MS/MS residue analytical method for propyrisulfuron in natural paddy field environment was developed. Propyrisulfuron residues in paddy water, soil, rice plants, brown rice and rice husk samples was extracted with 1.0 % acetic acid-acetonitrile (v/v) solution and separated on a reversed-phase C-18 column with a mobile phase of 0.1 % formic acid water-acetonitrile eluted by isometric elution (60/40, v/v), and quantified in high-resolution multiple reaction monitoring (MRMHR) scanning mode providing more accurate confirmatory information. The lower limit of quantification (LOQ) of propyrisulfuron in all the five paddy matrices was in a range of 1.24 similar to 3.85 mu g/kg, and all calibration curves showed good linearity (R-2 > 0.991) in a certain concentration range (10 similar to 1000 mu g/kg). At the spiked level of 10 similar to 200 mu g/kg, the intra-day and inter-day average recoveries and relative standard deviation were 82.80 similar to 106.93 % and 1.81 similar to 5.51 %, 83.05 similar to 105.84 % and 2.25 similar to 4.61 %, respectively, for analysis on three consecutive days, and there was a good retention time repeatability of 15 consecutive injections with RSD of 0.15 similar to 0.17 %, indicating a high sensitivity, specificity, accuracy and precision. All paddy filed environmental samples frozen at -20 degrees C were analyzed within 10 weeks after collection for a good storage stability. Propyrisulfuron dissipated in paddy water, soil and rice plants at application doses of 30, 45 and 60 g a.i./ha with half-lives of 1.37 similar to 1.81, 4.10 similar to 5.35 and 3.70 similar to 4.42 days in 2020, 1.44 similar to 2.04, 4.27 similar to 5.83 and 3.68 similar to 4.49 days in 2021, respectively. The final propyrisulfuron residual levels of two years in brown rice, rice husks and rice plants samples prior to harvest were lower than 8.18 mu g/kg, and its removal rate was in a range of 1.40 to 98.27 % by several simple available household technologies. Moreover, the chronic dietary risk in brown rice at recommended dose for Chinese residents of different age groups was low and acceptable for daily consumption.

Automated summary

A modified QuEChERS technology combined with UPLC-Q-TOF-MS/MS method was developed for the analysis of propyrisulfuron residue in natural paddy field environment. The method showed good accuracy and precision in quantifying propyrisulfuron residues in different paddy matrices. The study also found that the residual levels of propyrisulfuron were lower than the acceptable limit in brown rice, rice husks, and rice plants, and the residue removal rate could be effectively improved by simple household technologies.