Journal
FOOD ADDITIVES AND CONTAMINANTS PART A-CHEMISTRY ANALYSIS CONTROL EXPOSURE & RISK ASSESSMENT
Volume 30, Issue 10, Pages 1761-1769Publisher
TAYLOR & FRANCIS LTD
DOI: 10.1080/19440049.2013.820356
Keywords
green tea; black tea; tea infusion; neonicotinoids; pesticide residue; harvest waiting period
Funding
- National Natural Science Foundation of China [31270728]
- National Spark Program [2012GA710001]
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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 1.58days 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 20days were suggested for thiamethoxam, imidacloprid and acetamiprid, respectively, after application at their recommend dosages to ensure levels below a maximum residue limit (MRL) of 0.05mgkg(-1).
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