How to Select Solid Phase Extraction Cartridge?
Solid-phase extraction cartridge is a widely used technology in daily analysis and research applications to purify and concentrate analytes from various matrices. HAWACH SPE cartridges are produced and tested under strictly controlled conditions and are strictly checked before delivery in a standardized laboratory. SPE cartridges can improve and simplify separation, extend the life of the chromatographic column, and increase the detection limit. The extraction process is simple and fast, reduces solvent consumption, is easy to automate the operation, and has good recovery and reproducibility.
The SPE cartridge has a high sensitivity to small molecules and therapeutic peptides and can reduce the matrix effect of LC-MS/MS analysis, and can obtain the highest SPE recovery rate, with stable retention performance and reproducibility, wide selectivity of adsorbent, and various product specifications. It can be used in the detection of pesticides, veterinary drug residues, and pollutants in vegetables, fruits, and meat products, such as Sudan red, malachite green, and organophosphorus pesticides; detection of synthetic pigments in water; and the analysis composition of petroleum. Hawach offers Reversed Phase C18 SPE cartridge, Diol SPE cartridge, SAX SPE cartridge, and Mixed Mode Octyl(C8)/SCX SPE Cartridges for you to choose.
During the sample pre-treatment process, except for the selection of SPE cartridge sizes, there are still several factors that should be carefully considered.
Structure and specifications
Most common solid phase extraction columns are injection syringe type devices made of polyethylene. The device is equipped with two stoppers made of polypropylene or glass fiber and two stoppers. A certain amount of chromatographic adsorbent (filler) is filled in the middle of the sheet. With open upper end and lower end equipped with an outlet, after passing through the adsorbent, the liquid is discharged from the outlet. Through sample separation, purification, and concentration, the speed of sample liquefaction and meteorological analysis is improved, magazines are removed, the service life of chromatographic equipment is prolonged, and the pollution of the chromatographic system is avoided.
The first important factor to select an SPE cartridge is the filler. The principle is to ensure that the filler of the SPE cartridge has sufficient capacity to retain the target compound 100% on the column. On the other hand, the filler shall not be too much. The more the amount of the filler, the greater the amount of eluent will be required, which could be adequate for the target compound to be effectively eluted.
The capacity of the bonded silica cartridge is generally from 1% to 5% and the ion exchange cartridge is about 0.5 to 1.5 meq/g. Since there are many interferents except for the target compound, it is recommended that the filler capacity is more than twice the target compound content.
Pre-treatment Solvent Selection
For a reverse-phase cartridge or an ion exchange cartridge, the methanol or a polar organic solvent can usually be used as a pretreatment solution. Water or a buffer solution could be used as an equilibrium solution. For the pre-treatment of the normal-phase column, an elution solvent or a non-polar organic solvent would be a better choice.
Washing Solution Selection
When the target compound is a natural one, containing a hydrophobic non-polar filler (C4, C8, C18, for example), the cartridge is suggested to be washed with water or a buffer used for column equilibration. If the analyte has strong adsorption on the SPE cartridge, you need to enhance the washing effect with a water-soluble organic solvent added.Hope this guidance can help you a lot!
How to choose SPE cartridge
Since there are many advantages and applications for the solid-phase extraction cartridge, then how to choose it? We need to consider the adsorbent and column specifications. Appropriate adsorptive packing can make the interfering substance and the target component get good separation and meet the recovery requirements.
Choose according to the nature of the matrix:
|Matrix||Target compound||Main interferences||Extraction column|
|Soil, sewage||Hydrophobic organic pollutants||Humus||Reversed phase column C18, SLC|
|Fruits, vegetables, Chinese medicine, fruit juice, vegetable juice, fruit wine||Multiple pesticide residues||Carbohydrates, pigments, organic acids, phenols||NH2, Carbon/NH2|
|Weakly Polar Pesticides||Reversed phase column C18|
|Alkaline pesticides||Cation exchange column HLB|
|Acid pesticides||Anion exchange PAX|
|Blood, urine, animal tissue, dairy products||Neutral, weakly acidic, weakly basic drugs||Protein, fat||Reversed phase column C18, SLC|
|Basic drugs||Cation Exchange Column PCX|
|Acid drugs||Anion exchange PAX|
|grease||Fat-soluble vitamins, phospholipids, aflatoxins||Fat||Normal phase column silica, NH2, PSA|
We can select the adsorbent based on the target compound and matrix properties. After selecting the appropriate adsorbent, it is also necessary to select the appropriate column specifications according to the sample volume required for the verification.
Since the quality of the compound that the adsorbent of the extraction column can absorb is limited, once this value is exceeded, the target substance cannot be effectively retained, which greatly reduces the elution effect. Therefore, it is necessary to select the appropriate column specifications according to the number of components in the sample. The ideal solid phase extraction column type should be larger in inner diameter and length. As the column length increases, the corresponding number of plates is higher, the column inner diameter is larger, and the origin of the sample after injection is smaller (reflected on the column, the sample layer is thinner), and the resolution becomes larger.
The sample loading capacity and elution parameters of the extraction column are given below for reference:
|Column specifications||Max. sample volume||Min. elution volume|