How to Choose the Right SPE Cartridge to Meet Your Experiment Requirements?
About the advantages of Solid-Phase Extraction
Sample matrices vary widely, like vegetables, fruits, meat, eggs, milk, water, soil, rubber, textiles, etc., whether they are food or environmental samples, the complexity is also different. Simple samples can use the pre-processing method, but for complex samples, special pre-processing is required, such as using Solid-Phase Extraction (SPE for short) cartridges for further purification, separation of target substances and impurities, and further use in chromatography instruments. When you get a beautiful chromatogram, you will find that some pretreatment of the sample matrix will definitely use the SPE method.
As a sample pretreatment technology, SPE developed in recent years. It is a combination of liquid-solid extraction and column liquid chromatography technology, which is mainly used for the separation, purification, and concentration of samples. Compared with the traditional liquid-liquid extraction method, the recovery of the analyte can be improved, the analyte can be separated from the interference components more effectively, and the sample pretreatment process can be reduced. The operation is simple, time-saving, and labor-saving, which is widely used in medicine, food, environmental protection, commodity inspection, pesticide residue, and other fields.
Solid phase extraction instruments have unparalleled advantages: no special equipment and materials required; easy operation, no special equipment required; a good way to collect and enrich samples and improve detection sensitivity; faster than liquid-liquid extraction, saving solvent; automatic batch processing and good reproducibility.
About the choice of SPE cartridge
The choice of SPE cartridge packing and capacity is important.
SPE cartridge packing
First, select the appropriate packing based on the difference between the target compound and the interference, such as polarity, molecular weight, PKA value, etc. For reversed-phase, normal-phase, and adsorption solid-phase extraction columns, the mass of the extracted sample should not exceed 5% of the SPE column packing (the selectivity of the same adsorbent for different targets is different. This value is for reference only.); Ion-exchange solid-phase extraction columns must consider the capacity of ion exchange.
SPE cartridge capacity
In addition to the cartridge packing, the cartridge capacity should be considered, which needs to ensure the packing has sufficient capacity to retain 100% of the target compound. On the other hand, the packing is better not to be too much. The more packing, the greater the amount of solvent that will effectively elute the target compound.
Therefore, the SPE cartridge capacity must be considered when selecting the specifications of the SPE cartridge. Its capacity refers to the mass of a unit mass of packing that retains the compound with the main force. The capacity of the bonded silica gel column is generally 1% to 5%. Taking a 100 mg packed SPE cartridge as an example, its larger capacity generally does not exceed 5 mg. For the ion exchanger, the cartridge capacity is about 0.5 to 1.5 meq/g.
It is worth pointing out that, since we are mostly dealing with mixtures, in addition to the target compounds, there are many interfering substances. Therefore, when selecting the column specifications, the total amount of the target compound and the interferences that may be adsorbed under the extraction conditions must be considered instead of the target compound alone.
Otherwise, even if the target compound does not exceed the column capacity, the SPE column will retain some of the interfering compounds while retaining the target compound. Since the total of the two has exceeded the column capacity, as a result, some target compounds cannot be retained SPE column. Therefore, to be on the safe side, it is recommended that the column capacity be better than twice the estimated target compound content. Welcome to contact the Hawach team to learn more professional suggestions.