Matrix Interference Of QuEChERS
Extractions of all kinds are often matrix dependent. As for samples such as pesticide residue and food, most of them are not matrix dependent (except for some dry and oily samples).
However, some complex samples, such as tea leaf, traditional Chinese medicine, and spice, there will remain adsorption of pesticide residue by the matrix, no matter what kind of method you take. Because if there are impurities which are similar to the samples in structure, they are very difficult to be filtered by the process of QuEChERS. Of course, by using some methods such as regulating extractant, adjusting the PH value, adding salt, and changing the volume ratio, it will play a subtle role in the detection.
Moreover, in order to deal with complicated cases, we need to make high-quality chromatography-mass spectrometry detection. The instrument with high sensitivity will not only allow us to use extracting solution with a lower concentration but also largely fade-out matrix components coeluting with pesticides.
On the other side, if ruggedness or detection limits are compromised too much, gel filtration chromatography or extracting solution fractionation will be good solutions. At the same time, the requirement of data collecting, the duration of detection, the cost, and the instrument are the factors we must consider.