Determination of aflatoxin residues (1)

Aflatoxin is a group of difuranocoumarin derivatives with similar chemical structures.

In order to further strengthen the quality control of Chinese medicinal materials and further increase the safety index control items of Chinese medicinal materials, especially to strengthen the control of heavy metals and harmful elements, aflatoxins, and pesticide residues in Chinese medicinal materials, October 25, 2012, National Pharmacopoeia On the basis of the 2010 edition of the Chinese Pharmacopoeia, the committee issued a draft limit standard for heavy metals, pesticide residues, aflatoxins and other substances in traditional Chinese medicine

1.

The second supplement to the 2010 edition of the Pharmacopoeia revised this law and added a photochemical derivation method

(1) Principle

The basic principle of this method is that the sample is extracted by organic solvent, purified by immunoaffinity column, and then analyzed and determined by high performance liquid chromatography-post-column photochemical derivatization or iodine derivatization-fluorescence detector detection

The photochemical derivatization reaction is as follows:

(2) Instruments and utensils

High-speed homogenizer, oscillator; high-performance liquid chromatography unit with fluorescence detector (with 360nm excitation wavelength and emission wavelength greater than 420nm); photochemical derivatizer or post-column derivatization system; centrifuge; ultrapure water treatment system; ultrasonic extraction ; a total of Aspergillus flavus (B _.

(3) Test drug and test solution

Both methanol and acetonitrile are chromatographically pure; high-purity water; aflatoxin mixed reference substance; 0.

(4) Chromatographic conditions and system adaptability test

1.

Table 13-3 HPLC gradient elution program

2.

Operate according to the above conditions, the number of theoretical plates in terms of B should not be less than 5000, and the resolution of two adjacent chromatographic peaks should be greater than 1.

(5) Operation method

1.

2.

3.

(6) Matters needing attention

1.
This experiment should have corresponding safety and protective measures, and should not pollute the environment
.

2.
The glassware with residual aflatoxin liquid or waste residue should be placed in a special storage container (containing 10% sodium hypochlorite solution), soaked for more than 24 hours, and then clean the glassware with clean water
.
The experimental waste liquid also needs to be treated with sodium hypochlorite
.

3.
Ultraviolet rays are destructive to low concentrations of aflatoxin, so the mixed aflatoxin reference substance stock solution should be prepared in a brown volumetric flask and stored away from light
.
The mixed aflatoxin reference substance solution needs to be newly prepared before use, and be protected from light
.

4.
When the injection volume of the test solution exceeds 20ul, in order to ensure a good chromatographic peak shape, the test solution can be diluted to the mark with water at the end during the preparation of the test solution
.

5.
Accompanying recovery rate: the standard concentration is <1.
0ug/kg, and the recovery rate should be controlled within 60%～120%; the standard addition concentration is 1～10ug/kg, and the recovery rate should be controlled within 70%～110%
.

6.
The detection limit of the method based on aflatoxin B1 should not be higher than 0.
5ug/kg
.

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