Study Of Tracking Triazole And Carbamate Pesticides In Living Vegetables Based On A Novel Solid-phase Microextraction Fiber

Pesticide contamination in the environment and food has become one of the most serious problems in global agriculture.With the Ministry of Agriculture and Rural Affairs banning organochlorine,organophosphorus,and other highly toxic pesticides,the use of carbamates,triazoles,and other new pesticides has increased year by year,as has their environmental detection rate.The studies showed that triazole fungicides and carbamate insecticides can exhibit toxicity to non-target organisms.In addition,in real environments pesticides co-exist with other components and have complex interactions.Dissolved organic matter(DOM)is one of the most active chemical components in water and soil environments and can act as a natural sorbent and carrier,affecting the migration and bioavailability of pesticides in the environment.Humans are exposed to triazole and carbamate pesticides primarily through the consumption of foods containing pesticide residues,while vegetables are an important part of the daily diet and a major sink for pesticides.Current traditional pesticide detection methods can be permanently damaging or lethal to plants and are not suitable for repeat or long-term monitoring.In vivo solid-phase microextraction(SPME)sampling is a low-invasive technique that allows tracking the dynamics of contaminant concentrations in plants under non-lethal conditions and also allows the study of changes in endogenous metabolites.Fiber coatings of different materials have a significant effect on the sensitivity and selectivity of SPME.Based on this,a nitrogen-rich triazine-based porous polymer(NTP)material with high nitrogen content and a large number of nitrogen active adsorption sites was synthesized and prepared into novel SPME fibers,and the NTP-SPME fibers were used to investigate the bio-accumulation and elimination of triazole fungicides in live cabbage.Meanwhile,the effect of dissolved organic matter on bioaccumulation,transformation,and elimination of carbamate fungicides in live cabbage was investigated by an in vivo SPME sampling technique.The main results are as follows:(1)The NTP material has a high nitrogen content of 35.47%and has a high specific surface area and pore volume of 860 m~2/g and 0.84 cm~3/g,respectively.In addition,secondary amines(–C–NH–)and triazine nitrogen(–C=N–)in NTP provide a large number of nitrogen active sites,which facilitate the adsorption of triazole pesticides.Compared with commercialdivinylbenzene/carboxen/polydimethylsiloxane(DVB/CAR/PDMS),PDMS/DVB,and polyacrylate fibers,NTP-SPME fibers have much higher performance in adsorbing triazole fungicides than commercial fibers.(2)In following the bioaccumulation and elimination of triazole fungicides in live cabbage,the results of the study showed that all three pesticides showed a trend of decreasing followed by equilibrium during exposure and gradually decreasing during elimination.The highest concentrations of myclobutanil,propiconazole,and difenoconazole were reached on day 1 with 997.57±51.42,841.20±21.42,and 56.82±1.30ng/g,respectively.In addition,the concentration of difenoconazole was much lower than other pesticides throughout the experimental period,which might be caused by the difficulty of root uptake of cabbage due to its low solubility.(3)In experiments of tracking and monitoring the effect of dissolved organic matter on plant enriched carbamate pesticides,the results of the study revealed that the concentrations of carbamates and their metabolites in the two groups with and without the addition of typical DOM humic acid(HA)had similar variation trends,and there was no significant difference in the concentrations of the target analytes during the same period(p>0.05),which indicating that DOM has no significant effect on the enrichment and transformation of carbamate pesticides in living plants.In addition,isoprocarb,carbofuran,carbaryl,and its metabolites o-cumenol,carbofuran phenol,and 2-naphthalenol were all detected on day 0.25 in the group without HA exposure at 2452.5±349.12、2757.8±359.23、3593.2±722.54 ng/g and 142.85±14.815、749.73±125.79、1996.0±334.90ng/g,respectively,indicating that carbamate pesticides can be quickly absorbed and degraded by cabbage.