title: Comparison of the dissipation behaviour of three neonicotinoid insecticides in tea.
abstract: The dissipation behaviour of three neonicotinoids - thiamethoxam, imidacloprid and acetamiprid - was compared in tea shoots, in Chinese green and black tea, and after tea infusion in hot water. The simple and rapid analytical procedures for the quantification of these three residues in these matrices were developed using HPLC with ultraviolet (UV) detection. Degradation rates in tea shoots of neonicotinoids applied in either recommended or double dosages followed first-order kinetics, with half-lives of 1.62 or 1.58 days for thiamethoxam, of 2.45 or 2.67 days for imidacloprid, and of 3.24 or 3.85 days for acetamiprid, respectively. Through harvest and processing the residue retentions for thiamethoxam, imidacloprid and acetamiprid were 85.0%, 84.1% and 70.6% of the initial dosages in green tea, and 77.1%, 52.4% and 57.4% in black tea. These three residues all showed high transfer rates through green or black tea brewing of 80.5% or 81.6% for thiamethoxam, of 63.1% or 62.2% for imidacloprid, and of 78.3% or 80.6% for acetamiprid. Waiting periods between the last application and harvest of at least 12, 17 and 20 days were suggested for thiamethoxam, imidacloprid and acetamiprid, respectively, after application at their recommend dosages to ensure levels below a maximum residue limit (MRL) of 0.05 mg kg(-1).
authors.affiliation: a Key Laboratory of Tea Biochemistry & Biotechnology , Ministry of Agriculture & Ministry of Education, Anhui Agricultural University , Hefei , China.
authors.forename: Ru-Yan
authors.initials: RY
authors.lastname: Hou
authors.forename: Jin-Feng
authors.initials: JF
authors.lastname: Hu
authors.forename: Xiao-San
authors.initials: XS
authors.lastname: Qian
authors.forename: Ting
authors.initials: T
authors.lastname: Su
authors.forename: Xiao-Hui
authors.initials: XH
authors.lastname: Wang
authors.forename: Xiu-Xia
authors.initials: XX
authors.lastname: Zhao
authors.forename: Xiao-Chun
authors.initials: XC
authors.lastname: Wan
mesh_terms: D028241:Camellia sinensis / Q000009:adverse effects / Q000737:chemistry; D002681:China; D005506:Food Contamination / Q000032:analysis*; D005511:Food Handling; D006801:Humans; D007093:Imidazoles / Q000009:adverse effects / Q000032:analysis; D007306:Insecticides / Q000009:adverse effects / Q000032:analysis*; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000009:adverse effects / Q000032:analysis; D010078:Oxazines / Q000009:adverse effects / Q000032:analysis; D010573:Pesticide Residues / Q000009:adverse effects / Q000032:analysis; D011725:Pyridines / Q000009:adverse effects / Q000032:analysis; D013662:Tea / Q000009:adverse effects / Q000737:chemistry*; D000077922:Thiamethoxam; D013844:Thiazoles / Q000009:adverse effects / Q000032:analysis
chemical_list: D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010078:Oxazines; D010573:Pesticide Residues; D011725:Pyridines; D013662:Tea; D013844:Thiazoles; C082359:imidacloprid; C464485:acetamiprid; D000077922:Thiamethoxam