Brief Introduction And Application Of QuEchERS
The QuEchERS method is a simple, fast, safe, and inexpensive method for multi-residue analysis of pesticides. The main steps of this method are to use the samples containing 1% acetic acid in acetonitrile extraction, add the anhydrous magnesium sulfate and sodium acetate oscillation prompted the layered, subsequent dispersive solid-phase extraction, the extraction liquid transfer system to contain the PSA adsorbent, magnesium sulfate in the centrifuge tube, using Teflon coating of centrifugal pipe centrifugal, taking centrifugal liquid to automatic into the bottle used for GC/MS or LC/MS were used, and the stability and reliability are analyzed and evaluated. At the same time, this method can also be adjusted according to the types of analytical instruments available, detection limits, range of target pesticides, and differences in media used.
The matrix effect
Fluid to pledge the matrix effect is thought to be caused by the matrix is not volatile components and material under test, ionization produced during the competition. The matrix effect in the gas phase temperament generally attributed to the target through thermal injection port to the chromatographic column as a result of the matrix involved in the transmission process, reduce the thermal decomposition of unstable target; Or because the matrix shields the active site of the injector, thus reducing the adsorption of polar target by the active site. Then take the food with relatively complex composition as an example, the matrix affecting the recovery rate includes lipids, proteins, in addition to pigments, sugars, organic acids, salts, etc.
That’s how mass spectrometry kills you. They’re the little guys, the complex substrates.
The amino-functional group of PSA adsorbent can react with some acidic groups to remove polar organic acids, as well as some sugars and lipids.C18EC is a porous adsorbent with nonpolar physical adsorption, which can be used to remove lipids and sterols.GCB(graphitized carbon) has a good adsorption effect on chlorophyll and its polar small molecule interferers. Plastic-enhanced purification tube EMR, a new polymer, has a special selectivity for fats.
Summon the pre-treatment of the world of primal, QuEChERS pre-treatment of the pulse up, how fast good province, simple not rough
Extractive stages: salt package component is magnesium sulfate and sodium chloride and another buffer salt, the salting-out effect can make the water and acetonitrile liquid-liquid separation, in the process of extraction, can be different by adjusting the PH to increase the extraction efficiency of pesticide, for example, some pesticides that are sensitive to alkali will be relatively stable under the acidic system, you can use as AOAC and EN the kit with the buffer salt.
Purification stage: sample will happen after a high-speed centrifugal stratification, the top is the acetonitrile is dissolved with the target, take a certain amount of acetonitrile solution to advance joined the dispersible purification adsorbent in a centrifuge tube, food, for example, the use of purge line contains a certain proportion of PSA, MgSO4, adipose content is higher if the samples can be increased using C18; If the pigment content of the sample is high, GCB can be added. The purpose of optimization is good parallelism and a high recovery rate.
In recent years, the QuEChERS method has been widely used in the pretreatment of food safety test samples, and food safety test is also a major issue concerning the international people’s livelihood. Therefore, this paper discusses the basic principle of the QuEChERS method and its application in the pretreatment of food safety test samples.QuEChERS (Quick, Easy, being inexpensive, Effective, Rugged, and Safe), is a internationally in recent years developed a kind of latest fast sample preparation technique for agricultural product detection, developed by professor Anastassiades equals to the United States department of agriculture in 2003.
Pretreatment is the most time-consuming and laborious part in food inspection, and the quality of pretreatment determines the accuracy and precision of the analysis. The QuEChERS method has become a new technique of sample pretreatment which attracts much attention due to its characteristics of fast, simple, cheap, effective, reliable, and safe.
Application in the pretreatment of food safety test samples
QuEchERS method is applied in many fields, as long as the recovery rate of the object to be tested meets the requirements, and the substrate background to remove impurities meets the detection requirements, this method can be used to purify, food residues, animal residues, additives, illegal additives, plasticizer all fields may be involved. However, the QuEchERS method has been widely used in the detection of agricultural residues.