SN/T 5481-2022 in English

Analysis of standard technical framework

This method uses liquid chromatography-tandem mass spectrometry to detect gentamicin residues with a detection limit of 0.025 mg/kg, covering the serum/urine of cattle, pigs, sheep, chickens and pig feed matrices. The key technical features include:

Key operating points

1. Sample pretreatment

Serum samples needed to be naturally coagulated and separated, urine samples needed to be centrifuged at 12,000 rpm, and feed needed to be crushed to 20 g. Trichloroacetic acid solution was used to precipitate protein during extraction, and heptafluorobutyric acid was added to improve chromatographic behavior.

2. Instrument parameter optimization

The mass spectrometer used electrospray positive ion mode, and the main monitoring ion pairs were m/z 477.4→322.2 (quantitative ion) and 477.4→157.1 (qualitative ion), and the collision energies were set to 15 eV and 25 eV, respectively.

Method validation data

The validation results showed that the recovery rate of gentamicin in different matrices was between 80%-110%, and the intra-day precision RSD was <15%, which fully met the detection requirements of 0.05 mg/kg limit of quantification.

Implementation recommendations

1. Standard solutions need to be stored in plastic containers (-20°C) to avoid adsorption
2. Heptafluorobutyric acid solutions need to be protected from light (valid for 1 month)
3. It is recommended to use a matrix-matched standard curve to eliminate matrix effects

Technology evolution analysis

Compared with traditional microbial inhibition methods, LC-MS/MS methods have the advantages of strong specificity and high sensitivity. This standard innovatively uses heptafluorobutyric acid as an ion pair reagent, which effectively solves the problem of weak retention of gentamicin in reversed-phase chromatography.