[Study of deltamethrin detection method and its residual dynamics in Loincerae Japonicae Flos]

This paper reports the residual dynamics of deltamethrin and detection method in Loincerae Japonicae Flos to provide scientific basis for safe and appropriate use of deltamethrin. A field experiment was conducted in Fengqiu, Henan Province China. The field plots were sprayed with deltamethrin at the recommended dose and a high dose, respectively, and a control was set up, totally being 3 treatments with 3 replications. The flowers were picked at 2 hours, 1, 2, 3, 4, 5, 7, 9, 11, 13 and 15 days after pesticide application and then dried. The residue of deltamethrin was determined by gas chromatography method with electron capture detector for the above samples. Results showed that recoveries of deltamethrin ranged from 76.4% to 86.9%,and the relative standard deviation was below 11%,Linearity was observed over a range of 5-500 μg•L ⁻¹ with correlation coefficient was 0. 999 2. The established method meets the requirements of pesticide residue analytical methods. The degradation of deltamethrin followed the first order dynamics. The residue dynamic equation of the high dose and recommended dose deltamethrin were C=5.992 2e-0.338t and C=1.536 9e-0.31t respectively, and the half-life of deltamethrin in Loincerae Japonicae Flos was 2.09-2.24 days, which indicates that deltamethrin is an easily degradable pesticide. It is concluded that deltamethrin should be used in aphids occurring period and the safety interval was more than 7 days to ensure the safety of Loincerae Japonicae Flos consuming.