Easy to Understand the QuEChERS
Take the example of the pear test to check whether a pear is up to the standard.
Prepare the environment
The first step: Suitable Acetonitrile salting-out extraction environment was prepared. Make the pears into a puree, and take 10g to QuEChERS centrifuge tube of 50ml. Add extract solution (acetonitrile) and Salt into the acetonitrile solution(to create an aqueous environment ), then repeatedly shake to ensure that the pesticide is dissolved into the acetonitrile solution. QuEChERS Block ceramics to vortex can be added to accelerate the homogenization process.
Dispersive and extraction
The Second step, is dispersive and extraction twice. Vortex the sample vigorously for seconds and then centrifuge for minutes. The resulting sample will show three layers finally: acetonitrile and the extracted compounds of interest are the top one. The remaining solids from the sample are in the middle layer. Aqueous, containing the excess salts from extraction salt packed is the lower layer.
Transfer the top acetonitrile and the extracted compounds layer to the prepared tube and add into adsorbents as a purification agent which will remove matrix interferences. Vortex and then centrifuge the tube containing the adsorbents for minutes again. Remove the supernatant after secondary centrifugation and finally get the pure solution containing pesticide residues.
The third step is analyze. Analysis of the concentration and content of pesticides, determine whether the standard