SN/T 4537.2-2016 in English

Standard Overview and Technical Background

This standard replaces SN/T 2058-2008 and introduces new technologies and equipment such as HLB solid phase extraction cartridges and ELISA detectors. The detection limit is reduced to 0.1μg/kg, meeting the latest EU residue limit requirements.

Comparison of core testing processes

Key Technical Points

1. Reagent Preparation Specifications

Use a precision balance to weigh 0.01g of chloramphenicol standard. Dose to 100mL with methanol to prepare a 100μg/mL stock solution. Store at 4°C for no more than 3 months.

2. Sample Pretreatment

Place 2.0g of sample in a 50mL centrifuge tube. Add 8mL of 5% sodium sulfate solution, followed by 3mL of methanol eluent. Centrifuge at 6000r/min, then purify with an HLB column.

3. ELISA Assay

Use an microplate reader at 450 nm, with a standard curve range of 0.025-2 ng/mL and a correlation coefficient R ≥ 0.98. The assay must be performed at 20-24°C.

Implementation Recommendations

• Laboratories should regularly verify the inter-batch differences of ELISA plates.
• Each batch of testing should include a negative control and a 0.1μg/kg spiked sample.
• It is recommended that critical value samples be retested and confirmed by LC-MS/MS.

Technology Evolution Analysis

Main improvements of the 2016 version of the standard:
1) Introduction of immunoaffinity cleanup technology to reduce matrix interference
2) Use of EURO-PROXIMA kit to improve specificity
3) Shortening of detection time from 8 hours in the original standard to 4 hours