The Necessity of Adopting the QuEChERS Method
Pre-treatment is the longest and most labor-intensive part of food testing. The quality of pre-treatment determines the accuracy and precision of the analysis. QuEChERS method is a kind of high-precision sample pretreatment technology because it is quick, easy, cheap, effective, rugged, and safe. It uses the adsorbent filler to interact with impurities in the matrix to adsorb impurities to achieve impurity removal.
Main steps
The main step of the method is to extract the sample with acetonitrile containing 1% acetic acid, and then add anhydrous magnesium sulfate and sodium acetate to oscillate it to stratify, followed by dispersion solid-phase extraction, that is, the extract is transferred to PSA-containing adsorption.
In a centrifuge tube of magnesium sulfate, centrifuge with a Teflon-coated centrifuge tube, centrifuge the solution to an autosampler for GC/MS or LC/MS and analyze and evaluate its stability and reliability. At the same time, the method can be appropriately adjusted according to the type of analytical instrument available, the limit of detection, the range of the target pesticide, and the difference in the medium used.
Pesticide residues
Pesticide residues are a general term for all derivatives of pesticides and their toxicologically significant impurities, metabolic conversion products, and reactants that remain in organisms, agricultural products, and the environment due to the application of pesticides. The composition of agricultural products and food samples is complex.
The pesticide residue content is extremely low, generally in ppm and ppb, and there are also the influences of pesticide homologs, isomers, degradation products, metabolites, and conjugates. To remove the target simultaneous impurities, reduce chromatographic interference peaks, and avoid contamination of samples by detectors and columns, pretreatment is very important, accounting for about 70% of the workload.
Current problems
With the wide application of chemical pesticides in food, pesticide residues in food have become a topic closely related to consumer safety. At the same time, with the current import and export of large quantities of fruits and vegetables, these products are more attractive than their local products. To accommodate this growing demand, regulators will use a variety of analytical methods to monitor the quality of food. The requirement for these methods is to broaden the range of residue analysis and increase the number of samples that can be tested.
Features of the QuEChERS method
Extracting pesticide residues from food and preparing samples to be tested is a time-consuming, costly, and laborious process. In order to solve these problems, new multi-residue analysis methods such as QuEChERS have been developed to meet the increasing demand for sample loading. This new multi-residue analysis method improves the efficiency of the laboratory while improving the sensitivity of the subpray.
The increase in productivity is primarily achieved by increasing the quality of the sample purification product to reduce potential interference levels, resulting in a clean chromatogram and reduced possible instrument repair time.
Multi-residue analysis methods are suitable for many pesticides. QuEChERS has advantages, like being cost-effective, fast, sensitive, and high accuracy enough to meet regulatory requirements.
QuEChERS improves the efficiency of the analysis and is simple and inexpensive for analytical chemists to detect high-humidity foods, where the water content can cause problems with pesticide extraction. The dried food sample can also be fully activated with water for the detection of the QuEChERS method even before extraction.
