Determination of aflatoxins in milk powder by multifunctional purification column and liquid chromatography

Application of aflatoxins in milk powder

Sample extraction：

Measure 4g samples (solid samples need to be crushed and passed 1mm sampling sieve), add 16mL ultra-pure water to restore,

Take 4g recovery solution, add 10mL extraction solution (pure acetonitrile) and mix well;

Vortex for 6min, put into centrifuge (8000r/min centrifuge for 20min), and take supernatant as sample extraction liquid

Sample purification：

Step 1: Add 5mL of sample extract to the test tube

Step 2: Insert the rubber tip of the purification column into the test tube from the top of the test tube, and press the purification column down to the bottom of the test tube

Step 3: Pour the purified sample extract from the upper part of the column into the sample bottle or EP tube

Step 4: Take 2mL of the purified extract, blow nitrogen until dry, redissolve with 1mL or 0.5mL of the initial mobile phase, filter through the microporous membrane, and analyze on the machine

HPLCDetection condition：

Y Mobile phase: phase A, water; B phase, acetonitrile-methanol (50:50, v:v)

Equal gradient elution condition: A, 70%; B, 30%

Y column: C18 column (column length 250mm, column inner diameter 4.6mm, packing particle size 5μm)

Flow rate: 1.0mL/min

Y column temperature: 40℃

Y Sample size: 50μL

Fluorescence detection: excitation wavelength: 360nm; Emission wavelength: 430nm

Experimental result：

Liquid chromatogram of aflatoxin AFM1

(AFM1 concentration is 5ng/mL)

Liquid chromatogram of a blank sample of milk powder

Liquid chromatogram of milk powder additive sample

(AFM1 spiked concentration was 31.25ng/g)

Recovery rate of milk powder sample added standard

(AFM1 spiked concentration was 31.25ng/g)