Advantages of QuEchERS Pre-Processing
The QuEchERS pretreatment method has been widely adopted by a number of international pesticide residue analysis organizations including the American Association of Official Analytical Chemists (AOAC) because of its simplification of complicated pretreatment steps and the expansion of the range of pesticide residues extracted application.
Due to the complexity of the veterinary drug sample matrix, the different chemical properties of veterinary drugs and pesticides, and many other factors, the application of the QuEchERS pretreatment method in the early stage of the veterinary drug residues was limited.
However, with the continuous exploration and improvement of the experimental method, it is gradually applied to the pretreatment of certain veterinary drugs in food. The QuEchERS pretreatment method combines the multiple steps of extraction, separation, and purification in the experimental process into one step, which greatly reduces It saves the consumption of reagents and consumables, and saves the energy and time of the operators and inspectors.
QuEchERS pretreatment method has a wide range of sample detection and can be applied to a variety of fruits and vegetables, cereals, plants and meat, and other foods. The relevant standards established by the European Union are used to determine the pesticide residues in plant-derived foods.
Anastasiades has also established a relevant website platform that introduces, promotes, and exchanges QuEchERS methods with analysts from various countries. Combined with the properties of various samples to be analyzed, and improved QuEchERS method for various specific matrices was developed.
The method of sample preparation for QuEchERS is mainly divided into two parts, extraction and purification. Acetonitrile is the most suitable solvent for extracting a wide range of polar and multi-residue drugs. For the detection of some drugs, acetonitrile or acetonitrile with a volume fraction of 1% acetic acid can be selected as the extractant. And add a specific ratio of anhydrous magnesium sulfate and sodium chloride or sodium acetate to remove the water in the extraction environment.
To promote the extraction of drugs. Sometimes it is necessary to add an appropriate amount of sodium acetate or sodium citrate to adjust the pH value. The extraction liquid obtained by the extraction is centrifuged and separated into layers and is purified by the method of dispersion solid phase extraction. Add an appropriate amount of anhydrous magnesium sulfate to remove excess water, and add silica-based primary amine secondary amine bonded phase adsorbent (PSA) and C18 to purify complex matrix components, such as fatty acid, pigment, and carbohydrate interference.
The QuEchERS method has a good extraction effect when separating many types of drugs. Lopes et al. used the QuEchERS pretreatment method combined with triple quadrupole LC / MS detection technology to derivatize sulfonamides, quinolones, anthelmintics, avermectins, macrolides, and diamino in chicken samples. Many types of drugs with large differences in properties, including benzathine and benzathine penicillin, were tested and analyzed simultaneously.
This method has outstanding advantages such as a short detection period, easy operation, high recovery rate, and saving reagents. This method also has the advantage of saving time and reagents. In summary, the QuEchERS method meets the requirements of modern analysis. In order to simplify and optimize the application of this method in the field of veterinary medicine, many researchers have improved and optimized the original method to improve the separation effect of drugs.
An improved pretreatment method of QuEchERS combined with a high-performance liquid chromatography-tandem mass spectrometry detection method was used to detect the residues of tetracycline veterinary drugs in pork. The standard deviation is less than 7.7%, the method has high sensitivity, good repeatability, and easy and fast operation. Using the improved pretreatment method of QuEchERS, the analysis and detection methods of 30 commonly used drugs in tea were established, eluting with acetonitrile containing 0.1% acetic acid and methanol (volume ratio 5: 1), and the recovery rate reached 74%. 108%, the method sensitivity, precision, and accuracy all meet the testing requirements.
A pretreatment method for the analysis of 30 veterinary drug residues in fish meat was established. The sample was homogenized and then dispersed in water and extracted with nitrile. The results showed that the average recovery rate reached 63% -118% at the three-concentration spike level. It has high sensitivity and meets the testing requirements. Using QuEchERS pretreatment technology to establish seven kinds of sulfonamides in the chicken liver detection method, after extraction and purification of the DisQue extraction tube and purification tube, the recovery rate reached 70% -115%, the method is quick, simple, and easy to operate.
In terms of purifying agents, most analysts use anhydrous magnesium sulfate and C18 and also use PSA or anhydrous magnesium sulfate, C18, and PSA in different ratios. The veterinary drug base does not contain chlorophyll, so basically, no GCB is used. Norli et al. Improved the pretreatment method of QuEchERS and established the detection method of 22 drugs in tilapia, salmon, and salmon. Due to the higher fat content in tilapia and salmon, a mixed reagent of 75% acetonitrile and 25% tetrahydrofuran extracted from 22 kinds of drugs, the recovery rate has been significantly improved.