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SPE Equipment and Accessories
Extraction is required during sample analysis when filtration does not yield optimal results in sample preparation. The aim is to selectively “extract” the substances to be analysed from the sample. There are two methods: Liquid-Liquid Extraction (LLE) and Solid Phase Extraction (SPE). Another method to extract pesticides is QuEChERS (Quick Easy Cheap Effective Rugged Efective Safe), which is based on a combination of LLE and SPE. Here you will find devices & accessories for solid phase extraction (SPE) from all well-known manufacturers such as Agilent Technologies, Macherey-Nagel and many more. You will also find a great selection of SPE cartridges in our shop.
What is SPE?
Solid Phase Extraction (SPE) is a selective method for extracting target analytes. It is based on the principles of liquid chromatography. The analyte is present in solution and is applied to an SPE cartridge. At this point, interactions occur between the SPE sorbent and the analyte, including polar and non-polar interactions, ionic interactions, covalent bonding interactions, and multiple combined interactions. The goal of SPE is not delayed elution over time, but selective elution. In other words, by using appropriate solvents, one can control which sample components are eluted and which are retained. The analyte remains bound to the sorbent until all interfering substances have been removed. Only then is the analyte eluted. This eluate is collected and either further processed or used directly for analysis.
The advantage of SPE lies in the purity of the obtained extracts, making it particularly suitable for demanding analyses such as trace analysis. Another advantage is that SPE can be automated if necessary. For this purpose, well plates containing SPE sorbents are available. Another variant is online SPE, where an SPE column is placed in front of the analytical column. The analytes are retained on the SPE column while matrix components are eluted. The analytes are then eluted and transferred to the analytical column, followed by standard HPLC analysis.
Liquid-Liquid Extraction (LLE)
Liquid-Liquid Extraction (LLE) is a simple and cost-effective method for extracting substances from a given sample solution. It is based on the differing distribution of the analyte between a polar and a non-polar solvent. For this, the (aqueous) solution from which the analyte is to be extracted is mixed with a non-polar solvent and vigorously shaken. The resulting fine droplets of both solutions create a large surface area, allowing the analyte to migrate into the organic phase according to its polarity, until an equilibrium is established based on its partition coefficient. After phase separation, the organic phase can be collected and further processed, or transferred into a solvent suitable for HPLC and used directly for analysis.
The disadvantage of LLE is that only analytes with similar partition coefficients can be extracted in a single step. If a mixture of hydrophobic and hydrophilic analytes is present, they cannot be extracted simultaneously using this method. Moreover, matrix components with polarity similar to that of the analytes may also be extracted. Another drawback is that LLE is difficult to automate for large sample series. Additionally, depending on the scale of the process, considerable amounts of solvents may be required.