Choose Your Suitable SPE Cartridges

As we all know, the principle of the SPE method is the rule of similarity. So it is of great importance to choose the right paddings’ SPE Cartridges.

Based on separation modes, we can divide them into 3 groups:

1. Normal Phase C18, C18-Ne, C8, C2, PHE, CN

Utilizes the difference between the adsorption among the solid adsorbent paddings and the target compound in the sample and the adsorption of the sample matrix and the interfering compound, thereby achieving the purpose of separating and enriching the target compound.

2. Reverse Phase NH2, Silica, PSA

Uses a non-polar adsorbent (carbohydrate or polymer) on the stationary phase to separate the organic solute from the polar phase (water). The interaction between the non-polar materials is van der Waals attraction (adsorbent’s hydrophobicity).

3. Ion-Exchange SAX, SCX, PAX, PCX,

Ion-exchange SPE cartridges are the separation of ions with high energy interaction. Strongly polar solutes can be separated from highly polar water or other solvents. The exchange capacity of strong ion exchange resins is not affected by pH, and weak ion exchange resins are dependent on pH changes.

Two factors will be considered generally when choosing the SPE cartridges, which are the selection of adsorbents and the selection of cartridge specification. The proper adsorbents will separate the interfering materials and the target substances better and satisfy the retrieving demands at the same time. And there exist upper limits to the quality of compounds adsorbed by adsorbents. Once the quality of adsorbed compounds exceeds, the target substances will pass over the SPE  cartridge straightly instead of remaining in it.

Choose Your Suitable SPE Cartridges

1. The selection of adsorbents

Adsorbents should be selected according to the properties of target compounds and substrates. As to the examples, we can choose the adsorbents based on the principle that distinguishes target substances and the major interfering materials.

SubstratesTarget substancesMajor Interfering MaterialsSPE Cartridges
Soil, Sewagehydrophobic organic pollutantsHumic substancesC18, SLC
Fruits, vegetables, Chinese medicine, fruits syruppesticide residuesCarbohydrates, pigments, organic acids, phenolsNH2、Carbon/NH2
Pesticide residues with weak polarityC18
Alkaline drugsPCX
Acidic drugsPAX
GreaseLiposoluble vitamins, phospholipids, aflatoxinsfatNH2、PSA

2. The selection of cartridge specification

After choosing the proper adsorbent, we should choose the proper SPE cartridges with the best specification according to the volume of samples. And if the quality of the compounds to be measured is beyond the limit, the target substance will not remain effective, and the result of the elution is not good. Therefore, it is necessary to choose the proper specification.

SpecificationMaximum sample sizeMinimum elution volume

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