About The D-SPE Technology In QuEChERS Method
The QuEChERS method was first proposed by Anastassiades et al. of the US Department of Agriculture in 2003 and aims to replace the traditional pre-treatment method for pesticide multi residue detection in vegetables and fruits. The QuEChERS method is a sample pretreatment using dispersive solid phase extraction (d-SPE) technology, taking acetonitrile as the main extraction solvent, and N-propyl ethylenediamine (PSA), C18 and other materials with adsorption as a purification agent. Compared with traditional methods such as solid phase extraction, the QuEChERS method has the characteristics of fast speed, easy operation, low cost, high efficiency, strong durability, and safety.
The principle is to grind materials coated with various polymers such as C18 together with the sample to obtain a semi-dry mixture, and use it as a packing to fill the column, and then rinse the column with different solvents to remove various analytes.
The advantage is that it concentrates the process of sample homogenization tissue cell lysis, extraction, purification, etc. in the traditional sample preparation, without the need for tissue-homogenization, precipitation, centrifugation, pH adjustment, and sample transfer steps, which avoids the sample loss.
Stationary phase for D-SPE
Many stationary phases used in dispersion matrix extraction come from SPE. The so-called perfect adsorbent should be able to remove only impurities in the final extract without damaging the target. In all foods, these impurities include fat, carbohydrates, protein, water, and a small number of metal components, vitamins, and various natural products that vary from individual to individual.
The selective extraction step in the QuEChERS method removes some impurities (fat, water, protein, sugar). The design of the dispersion matrix extraction step is to further reduce residual impurities, because these impurities will affect the analysis and lead to matrix effects, reduce recovery, and reduce equipment ruggedness, such as fats and other acidic substances, chlorophyll, anthocyanins, etc.
Adding 150mg magnesium sulfate, 50-150mg PSA, 50mg C18, 7.5mg GCB per milliliter of extract for extraction is the best dispersion matrix extraction solution we know for pesticide residue analysis in food, which can provide high recovery in a wide concentration range. These steps-using other adsorbents, changing their dosage, adjusting PH or solvent composition, de-fatting n-hexane, may make the impurities better removed, but this will reduce the recovery of pesticide residues. Molecular imprinting technology (MIPs) can specifically remove certain types of impurity components, which is a good supplement without reducing the recovery of the test substance.