Purifying Agent Adopted In QuEChERS
The purifying agent holds an important position in the QuEChERS pre-treatment method. An appropriate selection and application of it would be necessary for the users to improve the efficiency of purification and accuracy of the sampling detection result.
Selection of purifying agents
There are two kinds of the purifying agent that are widely adopted in the practical application of QuEChERS – PSA and C18. PSA mainly removes polar substances, such as sugars, fatty acids, organic acids, phenols, and lipophilic pigments. And the C18 is the most significant purifying agent for QuEChERS, which mainly adsorbs non-polar substances, such as fat through its silica matrix adsorbent.
Both of them have a slight infection on the recovery rate of the samples, but they are not ideal for the purification effect of pigment. On the contrary, the adsorption effect of CGB on the pigment can reach 90%. due to its low recovery rate during the detection of multi-residue pesticides, CGB is generally avoided to be used.
Dosage of purifying agents
Usually, the dosage of PSA and C18 is chosen as 200mg, which has a better purification effect and higher recovery rate. For the dosage of GCB, it is usually 10mg in terms of the color shade of extract liquor.