SN/T 5121-2019 in English

Principle of the method

The ivermectin in the sample was extracted by acetonitrile using Liquid chromatography-tandem mass spectrometry (LC-MS/MS) detection technology. After separation on a C18 chromatographic column, qualitative and quantitative analysis was performed in multiple reaction monitoring mode (MRM). The internal standard method used deuterated ivermectin (d2) to ensure detection accuracy, and the method detection limit reached 10μg/kg.

Liquid chromatography parameters

• Chromatographic column: C18 (100mm×4.6mm,2.6μm)
• Mobile phase: A-5mmol/L ammonium acetate + 0.1% formic acid aqueous solution, B-acetonitrile
• Gradient program: 50%B→95%B(12min)→50%B(12.1min)

Mass spectrometry parameters

• Ion source: ESI positive ion mode
• Monitoring ion pairs: m/z 892.8→569.7 (quantitative), 307.5 (qualitative)
• Collision energy: 21.19V (quantitative), 59.90V (qualitative)

Compared with the early ELISA method, this standard improves the detection specificity by 300% and solves the cross-reaction problem of avermectins. New in the 2019 version:

1. Isotope internal standard quantitative technology
2. Low-temperature centrifugation anti-degradation measures
3. Matrix effect compensation plan

Critical control points

• Sample storage: Blood needs to be frozen at <-18℃ to avoid repeated freezing and thawing
• Pretreatment: Strictly control the nitrogen blowing temperature ≤40℃ to prevent the target from decomposing
• System suitability: 10μg/L standard solution is required to verify the sensitivity every day

Solutions to common problems