Persistence, dissipation and dietary risk assessment of sulfoxaflor in wheat agro-ecosystem under tropical climatic conditions

ABSTRACT

Sulfoxaflor is a systemic sulfoximine insecticide, used to control sucking pests in different agricultural crops including wheat. However, the information regarding its residual fate in wheat agroecosystem under tropical environment and the associated dietary risk are still obscure. Therefore, a supervised field experiment was conducted in wheat comprising the application of sulfoxaflor 12% (w/v) SC at 30 and 60 g a.i. ha⁻¹ in two consecutive seasons. An optimised method for estimation of sulfoxaflor residues using modified QuEChERS technique was developed and validated. The extracting solvent ethyl acetate + cyclohexane (9 + 1 v/v) along with the clean-up combinations viz. 75 mg PSA+25 mg GCB+150 mg magnesium sulphate for wheat plant and straw and 75 mg PSA+75 mg C18 + 150 mg magnesium sulphate for grain produced satisfactory recovery, minimum matrix interference and optimum peak shape. The average recovery, repeatability and within-laboratory reproducibility of sulfoxaflor in wheat substrates ranged between 90.66% and 103.55%, 2.67–5.17% and 3.05–8.15%, respectively, and the limit of quantification was estimated 0.01 mg kg⁻¹. Sulfoxaflor was stable up to 60 days in wheat matrices under storage (−20°C). The dissipation of sulfoxaflor in wheat plants followed first-order kinetics and the overall shorter persistence in Season I and II ranged between 1.05–1.14 and 2.44–2.47 days (T_{1 –} T₂), respectively. The deviation in the persistence of the compound between two seasons due to variation in climatic parameters was observed to be statistically significant. The estimated pre-harvest interval of sulfoxaflor ranged between 4.95–5.34 (Season I) and 11.37–11.55 days (Season II). Besides, the terminal residues of sulfoxaflor were below quantification limit in the harvested wheat products, and the estimated long-term dietary risk of sulfoxaflor was observed to be negligible. Therefore, it was expected that the application of this insecticide in wheat cultivation should pose no residual toxicity and the harvested wheat products can be considered safe for human consumption.

KEYWORDS:

• Sulfoxaflor
• QuEChERS extraction
• LC-MS/MS analysis
• wheat
• dissipation
• dietary risk assessment

Acknowledegment

The authors are indebted to the Export Testing Laboratory (NABL accredited ISO/IEC 17025: 2005 certified), Bidhan Chandra Krishi Viswavidyalaya for extending infrastructure facilities and Dow AgroSciences India Pvt. Ltd. for providing analytical reference materials and formulation.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

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