To investigate the dietary exposure risk of flonicamid application on Lonicerae JaponicaeFlos and the effect of flonicamid on constituents of Lonicerae Japonicae Flos, field experiments were conducted in Fengqiu, Henan province, and flonicamid residue in samples collected was detected by gas chromatography equipped with electron capture detector (GC-ECD). And chlorogenic acid and luteoloside were determined by HPLC. Dietary exposure risk assessment was conducted through comparing the estimated daily intake (EDI) which was calculated by using the consumed residual level along with the acceptable daily intake (ADI). The effect of flonicamid on chlorogenic acid and luteoloside were obtained by ANOVA statistical analysis and LSD-t test. The results showed that the terminal-residue contents of flonicamid were under 1.6 mg kg -1 . And risk quotient ranged from 0.0011 to 0.0028, indicating the long-term exposure to flonicamid residual through consumption of Lonicerae Japonicae Flos in consumers was relatively low. Flonicamid could suppress the generation of luteoloside, so it was not advised to be used in L. japonica flowering phase. The study aims at providing the useful suggestion on the reasonable flonicamid usage and the reference for the establishment of maximum residue limits (MRLs) of flonicamid in Lonicerae Japonicae Flos.
Materials and methods
Standards, reagents, instrumentsReference standard of flonicamid (100 mg/L) was purchased from AccuStandard, Inc (USA). The standards of CA and luteoloside were obtained from Shanghai Aladdin bio-chem technology company, LTD (China).Analytical grade solvents, including ethanol, acetonitrile, toluene, glacial acetic acid, and anhydrous sodium sulfate, were obtained from Beijing chemical works company (China).HPLC-grade acetone, acetonitrile were obtained from Fisher Scientific (UK). The NH 2 (500 mg, 6 mL) SPE cartridges (500 mg, 6 mL) was got from Anpel laboratory technologies Inc. (China).The GC analyses were performed by 6890N gas chromatography equipped with μ-ECD (Agilent technologies, USA). And the column DB-1701 (30 m×0.32 mm×0.25 μm, Agilent technologies, USA) was applied for separation. HPLC analyses were performed using the e2695 liquid chromatograph and 2996 PDA detector (Waters, USA). Separation was achieved by using an Rsprosil-Pur 120 C 18 column (4.6 mm×250 mm, 5 μm, Dr.Maisch, German).Meanwhile, the ultrasonic cleaner (SB-2500DT, Ningbo scientz biotechnology company, China), the vortex mixer (WH-1, Shanghai huxi analytical instruments, China), the rotary vacuum evaporator (LABOROTA-4000, Heidolph Inc., Germany), the vacuum pump (SHB-B, Zhengzhou greatwall scientific company, China) and the centrifuge (80-2, Jintan medical-equipment company, China) were used, too.
Field trialsField experiments were implemented in Dongzhonggong village, Chengu town, Fengqiu For terminal residue experiment on L. japonica flonicamid (10%, Water dispersible granule) was sprayed at two dose levels of 60 g of effective ingredient per hectare (g a.i/ha, the recommended...