SN/T 5168-2019 in English

Analysis of the core content of the standard

Key technical points

1. Sample pretreatment optimization

The standard method is to use β-glucuronidase/arylsulfatase for enzymatic hydrolysis, and then adjust the pH to 10 and then use ether for extraction. The key control points include:

• Enzymatic hydrolysis conditions: 37℃ water bath for 2 hours
• Extraction solvent: 20mL ether, which must be operated in a fume hood
• Purification method: anhydrous magnesium sulfate + sodium chloride combination for dehydration

2. Instrument analysis parameters

Use β-glucuronidase/arylsulfatase class=instrument>C18 chromatographic column (100mm×3.0mm,3.5μm) was used for separation, and the gradient elution program showed:

0-1min: 30%B → 2-3min: 70%B → 4-8min: 95%B → 8.1min: 30%B

The mass spectrometer monitoring ion pairs were 333.0/99.0 (quantitative) and 333.0/159.2 (qualitative), and the collision energies were 40eV and 30eV, respectively.

Recommendations for the implementation of the standard

1. Quality control measures

1. Blank test and spike recovery should be carried out simultaneously for each batch of samples
2. Establish a matrix-matched standard curve (R²≥0.99)
3. Regularly verify the mass spectrometer resolution (unit mass resolution)

2. Key points for method validation

The following should be verified when the laboratory implements the method for the first time:

• Specificity: There is no interference peak in the blank matrix
• Sensitivity: S/N≥3 corresponds to LOD of 20μg/kg
• Precision: RSD≤15%(n=6)

Analysis of technological evolution

Compared with the traditional GC-MS method, the LC-MS/MS used in this standard has obvious advantages:

This standard was implemented in May 2020, reflecting my country's technological progress in the field of veterinary drug residue detection, especially the detection capability of synthetic steroids has reached the international advanced level.