SN/T 5116-2019 in English

Technical background and scope of application of the standard

SN/T5116-2019 was formulated by the General Administration of Customs. It established technical specifications for the detection of malachite green, crystal violet and their metabolites in response to the demand for veterinary drug residue control in edible animals and feed during import and export. This standard uses liquid chromatography-mass spectrometry/mass spectrometer as the core detection equipment, covering aquatic products such as fish, shrimp, crab and shellfish and various feed matrices.

Principle and key technologies of the method

Optimization of chromatographic mass spectrometry conditions

The standard stipulates that a C18 column (1.8μm) should be used for separation, and the mobile phase is 5mmol/L ammonium acetate (containing 0.1% formic acid) and acetonitrile gradient elution. In the mass spectrometry parameter setting, the qualitative ion pair of malachite green is 329.4/313.3 (CE=49V), and that of crystal violet is 372.4/356.3 (CE=50V).

Implementation recommendations and precautions

1. Different matrices need to strictly distinguish the pre-treatment process, and aquatic samples should avoid losses caused by the use of cation exchange columns
2. Internal standards (D5-malachite green, etc.) should be added at the initial stage of extraction, and the correction rate should be controlled at 85-115%
3. Regularly verify the contamination of the mass spectrometer ion source, and clean the ion lens when the crystal violet response value drops by 30%

Method validation data

Multi-laboratory validation shows that within the 0.5-100μg/kg addition concentration range, the recovery rates of the four target substances are stable between 84-117%, and the relative standard deviation (RSD) is ≤15%. The detection precision of leuco crystal violet in fish matrix is the best (RSD=4.8-9.2%).