The research aims to develop a rapid and easy analytical method for methoprene using liquid chromatography- tandem mass spectrometry (LC-MS/MS). A simple, highly sensitive, and specific analytical method for the determination of methoprene in livestock products (beef, pork, chicken, milk, eggs, and fat) was developed. Methoprene was effectively extracted with 1% acetic acid in acetonitrile and acetone (1:1), followed by the addition of anhydrous magnesium sulfate (MgSO4) and anhydrous sodium acetate. Subsequently, the lipids in the livestock sample were extracted by freezing them at -20oC. The extracts were cleaned using MgSO4, primary secondary amine (PSA), and octadecyl (C18), which were then centrifuged to separate the supernatant. Nitrogen gas was used to evaporate the supernatant, which was then dissolved in methanol. The matrix-matched calibration curves were constructed using 8 levels (1, 2.5, 5, 10, 25, 50, 100, 150 ng/mL) and the coefficient of determination (R2) was above 0.9964. Average recoveries spiked at three levels (0.01, 0.1, and 0.5 mg/kg), and ranged from 79.5-105.1%, with relative standard deviations (RSDs) smaller than 14.2%, as required by the Codex guideline (CODEX CAC/GL 40). This study could be useful for residue safety management in livestock products.

ABSTRACT
Materials and Methods
    시약 및 검체
    표준원액 및 표준용액의 조제
    LC-MS/MS 기기분석 조건
    추출 및 정제
    시험법 유효성 검증
Results and Discussion
    기기분석 조건 확립
    추출 및 정제조건 최적화
    시험법 유효성 검증
Acknowledgement
국문요약
Conflict of interests
ORCID
References

• 박은지(식품의약품안전처 식품의약품안전평가원 식품위해평가부 잔류물질과) | Eun-Ji Park (Pesticide and Veterinary Drug Residues Division, Food Safety Evaluation Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Cheongju, Korea)
• 김남영(식품의약품안전처 식품의약품안전평가원 식품위해평가부 잔류물질과) | Nam Young Kim (Pesticide and Veterinary Drug Residues Division, Food Safety Evaluation Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Cheongju, Korea)
• 박소라(식품의약품안전처 식품의약품안전평가원 식품위해평가부 잔류물질과) | So-Ra Park (Pesticide and Veterinary Drug Residues Division, Food Safety Evaluation Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Cheongju, Korea) Corresponding Author
• 이정미(식품의약품안전처 식품의약품안전평가원 식품위해평가부 잔류물질과) | Jung Mi Lee (Pesticide and Veterinary Drug Residues Division, Food Safety Evaluation Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Cheongju, Korea)
• 정용현(식품의약품안전처 식품의약품안전평가원 식품위해평가부 잔류물질과) | Yong Hyun Jung (Pesticide and Veterinary Drug Residues Division, Food Safety Evaluation Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Cheongju, Korea)
• 윤혜정(식품의약품안전처 식품의약품안전평가원 식품위해평가부 잔류물질과) | Hae Jung Yoon (Pesticide and Veterinary Drug Residues Division, Food Safety Evaluation Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Cheongju, Korea)