SN/T 5123-2019 in English

Technical background and scope of application of the standard

SN/T 5123-2019 is a mandatory industry standard for the control of histamine content in imported and exported feeds issued by the General Administration of Customs of my country. It stipulates two detection technology paths: spectrophotometer colorimetry and enzyme reader immunosorbent assay. The standard was officially implemented on March 1, 2020 and is applicable to the import and export inspection of animal-derived feeds such as fish meal and meat and bone meal.

Comparison of core detection methods

Analysis of key operation points

1. Technical specifications of colorimetry

Color reaction control:The pH value of the reaction system must be strictly maintained in the range of 3.5-4.0. When using 70% ethanol as the extractant, the centrifugal speed should be controlled above 2000r/min.

Standard curve preparation:Six concentration gradient standards of 0, 2.5, 5, 10, 20, and 40 mg/kg are required, and the absorbance is measured at a wavelength of 450nm.

2. ELISA Method Precautions

ELISA plate incubation: The standard clearly requires that the reaction temperature be controlled at 20-25°C, and the incubation time error should not exceed ±1 minute. When using the RIDASCREEN kit, attention should be paid to the accurate dilution of the 50-fold concentrated buffer.

Result interpretation: When the sample absorbance value is lower than the lowest standard point (0.5μg/kg), the verification experiment should be carried out in accordance with clause 5.4.3 of the standard.

Limit Standards and Judgment Rules

Implementation suggestions and common problems

Method selection:For large-scale screening, the ELISA method is recommended, and the colorimetric method is used for suspicious sample review. Note that the standard curve of different brands of kits needs to be re-validated.

Quality control: Blank control and spike recovery experiments should be added to each batch, and the recovery rate should be controlled between 80%-120%. The standard particularly emphasizes that the experimental water must meet the requirements of GB/T 6682 secondary water.

Technology evolution analysis

Compared with the old 2003 version of the standard, the main improvements of the 2019 version include:

1. Add immunological detection methods, and increase sensitivity by 10 times
2. Refine the sample pretreatment process and clarify the centrifugation parameters
3. Introduce standardized requirements for the number of ELISA plate washes