Simultaneous determination of thiamethoxam and its metabolite clothianidin by LC-MS/MS in goji berry and soil

ABSTRACT

In this study, an effective analytical method for simultaneous determination of thiamethoxam and its metabolite clothianidin in goji berry and soil was developed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The recoveries of the compounds in goji berry and soil at the levels of 0.005, 0.02, and 0.1 μg kg⁻¹ were 84.7–98.9% and the relative standard deviations (RSDs) were 0.9–3.2%. The limits of detection (LOD) for both compounds in goji berry and soil matrices were 0.001 mg kg⁻¹; the limits of quantification (LOQ) were 0.005 mg kg⁻¹ for both compounds in two matrices. The dissipation and final residual experiments in 2016 with the commercial formulation of dinotefuran • thiamethoxam 30% suspension concentrate (SC) was conducted in goji berries in northwest China (Qinghai, Gansu, Inner Mongolia, and Ningxia). Thiamethoxam was dissipated fast in goji plant ecosystem with half-lives were 1.08–1.01 and 2.04–4.25 days in goji berry and soil. The final residues of thiamethoxam were <0.005–0.382 and <0.005–1.120 mg kg⁻¹ in goji berry and soil, respectively.

KEYWORDS:

• Goji berry
• thiamethoxam
• clothianidin
• dissipation
• final residue

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Applied Basic Research of Qinghai Science & Technology Department (2018-ZJ-716), National Natural Science Foundation of China (31860512), and the National Key R&D Program of China (No.2016YFD0200504)