GB/T 40462-2021 in English

This standard establishes a method for the determination of 19 veterinary drug residues in organic fertilizers, including 15 sulfonamides and 4 quinolone compounds, by liquid chromatography tandem mass spectrometry. The method adopts a dual extraction system of Na₂EDTA-Mcllvaine buffer and acetonitrile-acetic acid solution, and is purified by HLB solid phase extraction column, which significantly improves the recovery rate of the target in a complex matrix.

1. Sample pretreatment optimization

The use of Na₂EDTA-Mcllvaine buffer (5.8) at pH 4.0 can effectively chelate metal ions and prevent the target from combining with metal elements in fertilizers. The acidic environment of acetonitrile-acetic acid solution (9:1) is conducive to improving the extraction efficiency of sulfonamide drugs.

2. Mass spectrometry condition setting

In the electrospray ionization source (ESI+) mode, the collision energy (15-35eV) and cone voltage (20-30V) were optimized for different compounds. For example, for sulfonamides, the characteristic fragment ion of m/z 156→92 is mainly monitored, while for quinolones, the parent ion [M+H]⁺ is used as the quantitative ion.

Laboratory Preparation Requirements

• A temperature-controlled centrifuge (≥4000rpm) and a nitrogen-purging concentration device are required.
• It is recommended to use Waters Oasis PRiME HLB or equivalent purification columns.
• The mobile phase must be prepared and used immediately. The formic acid aqueous solution should not be stored for more than 24 hours.

Quality Control Measures

1. Each batch of samples should include a method blank and a spike recovery (the recommended spike level is 0.1mg/kg).
2. The retention time deviation must be controlled within ±2.5%.
3. The ion abundance ratio should meet the tolerance requirements of Standard Table 3.

With the popularity of organic fertilizer made from livestock and poultry manure, the risk of veterinary drug residues circulating through the food chain has become increasingly prominent. This standard is the first to systematically establish a detection scheme for multiple veterinary drug residues in fertilizer matrices. Compared with the agricultural industry standard NY/T 316-1997, the detection types have been expanded from a single sulfonamide to 19 compounds, and the method sensitivity has been increased by 10-100 times.

The typical spectra provided in Appendix B (Figures B.1-B.3) are of great reference value for compound identification, especially when the retention time is in the range of 4-6 minutes, there is a risk of co-elution of multiple sulfonamide drugs, which needs to be strictly confirmed according to the ion pairs set in Table 2.