◆ Introduction

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QuEChERS is a solid phase extraction method for the detection of pesticide residues in foods. Its name stands for "Quick", "Easy", "Cheap", "Effective", "Rugged", and "Safe". The QuEChERS process is divided into three stages: homogenization, extraction, and clean-up. These steps are quick and easy to implement and are less prone to errors.

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◆ Steps

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1. The sample of interest (fruits, vegetables, tea leaves, etc.) is homogenized and 10 grams is added into a 50 mL centrifuge tube.

2. An acetonitrile solution containing 1% acetic acid and an internal standard (optional) is added to the sample for the extraction process.​

3. The mixture is then vigorously shaken for 1 minute.

4. To avoid an exothermic reaction that may degrade the samples, the extraction salts (Anhydrous Magnesium Sulfate and Anhydrous Sodium Acetate) are added in this buffering and drying step.

5. The mixture is then vigorously shaken again for 1 minute.

6. The sample is centrifuged and the upper organic layer is collected.

7. The collected organic layer is placed in a  15 mL centrifuge tube with, depending on the sample type, certain chemical powders for dispersive SPE clean-up.

8. The sample is shaken vigorously for 30 seconds and centrifuged.

9. The top organic layer is transferred to a sample vial for analysis by GC or LC.

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◆ QuEChERS have the following advantages:

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- Minimum use of chemicals (environmentally friendly). It can reduce the amount of organic solvents used by up to 50%.

- Non-labor intensive (few steps needed).

- Quick: The powder is already prepared and can be directly added to each test tube, saving analysts time and effort.

- No chlorinated solvents.

- Applies to a wide range of pesticides.

- Has high recovery rate and low coefficient of variation.

- Reduces the amount of glass and plastic containers needed for the traditional process.

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