Thiamethoxam (TMX) is one of the neonicotinic insecticides, CAS No. 153719-23-4. It is a competitive regulator of nicotinic acetylcholine receptor (nAChR), which acts on the acetylcholine receptor of insect nervous system, causing a series of symptoms of insects from overexcitement to lethargy and paralysis. China's GB 2763-2019 Maximum Residue Limits of Pesticides in National Food Safety Standards stipulates that the ADI value is 0.08mg/kg bw, which clearly stipulates the residue limits of thiamethoxam in oils, vegetables, fruits, dried fruits, beverages, condiments and other foods. In order to ensure the traceability, comparability and accuracy of the detection results of thiamethoxam residues in food in China, the Chinese Academy of Metrology has developed the thiamethoxam solution reference material. The purity of raw materials adopts the mass balance method and the quantitative nuclear magnetic resonance legal value. The quantity value is 99.4%, and the expanded uncertainty is 0.4%（ k =2）； The solution standard substance adopts the legal value of weight and volume, with the value of 1.00mg/mL and 10.0 μ g/mL, and the relative expanded uncertainty is 1%（ k =2）。 This reference material can meet the requirements of national food safety standards GB 23200.8, GB 23200.9, GB 23200.11, GB 23200.39, GB 23200.121, GB/T 20769, and GB/T 20770. It needs to be stored at room temperature and away from light, and the validity period is 15 months.
reference:
1. Li, X.; Yang, B.; Ma, W.; Tu, M.; Zhang, Y.; Ma, Z.; Zhang, Q.; Li, H., Impurity identification in thiamethoxam by high resolution mass spectrometry and computer assisted elucidation.Anal. Bioanal. Chem.2022,414(24), 7203-7210.
2. Li, X.; Zhang, W.; Zhou, S.; Li, X.; Tu, M.; Zhu, Y.; Zhang, Q.; Li, H., Purity assessment of thiamethoxam using mass balance and quantitative nuclear magnetic resonance.Microchem. J.2023,191, 108874.
3. Tu Mengling; Yang Bingxin; Zhu Yunxiao; Li Xianjiang, Research progress of certified reference materials for new nicotine pesticides Metrology Science and Technology 2023,67 (3), 65-71
GBW08771 Reference material of thiamethoxam solution in acetonitrile
GBW08772 Reference material of thiamethoxam solution in acetonitrile
