SN/T 1605-2017 in English

Analysis of the core content of the standard

This standard uses liquid chromatography-mass spectrometry/mass spectrometry to detect the residues of five herbicides in plant products such as rice and oranges, with a detection limit of 10 μg/kg. The key technical improvements include:

Key technical innovations

1. Pretreatment optimization

Oasis MCX solid phase extraction column was used to replace the traditional alumina column, and the recovery rate was increased by 15-20%. Different extraction schemes were used for different matrices:

• High-water samples (spinach/orange): direct extraction with acetonitrile
• Dry samples (rice/corn): extraction after infiltration with water

2. Instrument parameter optimization

The chromatographic column was a Chromolith® High Resolution RP-18e monolithic column, with a gradient elution of 0.6 mL/min (5mmol/L ammonium acetate-acetonitrile system), and the five compounds were completely separated within 8 minutes.

Method Validation Data

In 6 matrices spiked with 0.01-10 mg/kg concentration levels, the recovery data showed that:

• Cyanazine: 73.0-115%
• Fluoromethiocarb: 73.0-115%
• The recovery rate of soybean matrix is low, it is recommended to increase the extraction time

Implementation Recommendations

1. For highly pigmented samples (such as spinach), it is recommended to add a 2 mL hexane degreasing step
2. When tuning the mass spectrometer, pay attention to the optimization of the collision energy of 217.1→214.1 (cyanazine) and 233.1→72.0 (fluoromethiocarb)
3. It is recommended to intersperse matrix standards in each batch of samples to compensate for ion suppression effects