QuEChERS has undergone several major optimization changes since it was developed. The first improvement was the use of the buffer in the extraction process. The recovery of some compounds is susceptible to the influence of pH, which can be effectively solved by using the buffer. The second improvement is the purification effect.
The use of C18 filler together with PSA can improve the purifying effect of samples, especially for oil-rich samples. The third is to select suitable adsorbents for different sample matrices to improve the purification effect. For example, adding a small amount of graphitized carbon black can adsorb chlorophyll, carotenoids and other impurities.
The Application of QuEChERS Kits
In fact, the application of QuEChERS kits is the extraction of samples by acetonitrile or acidic acetonitrile after homogenization. Afterward, the laboratory workers use QuEChERS salts, including magnesium sulfate and buffer salt, to make salting stratification.
Also, by using the dispersive solid-phase extraction and combination of other adsorbents and most of the chaff interferents, such as organic acid, aliphatic acid, and carbohydrate in the base materials. Lastly, operating the elimination by centrifugation and take the supernatant to make analysis, so that the laboratory workers can achieve the aim of purification.
In general, the steps for using QuEChERS Kits include five steps.
1. Grinding and weighing of samples.
2. Extraction and separation by acetonitrile of single solvent.
3. Eliminating water by adding magnesium sulfate and another kind of salt.
4. Eliminating impurities by adding PSA and another adsorbent.
5. Using GC-MS, LC-MS to test the liquid supernatant.
Basically, the QuEChERS salts include buffer salt and anhydrous magnesium sulfate. Under normal conditions, the buffer salt can make the extraction environment at a mild PH level, and make sure the target compound stay stable. On the other side, the anhydrous magnesium sulfate has the water absorptivity, and can completely separate the acetonitrile extraction solution from the water in the base material.