The Concept and Basic Principles of Solid Phase Extraction
The Concept and Basic Principles of Solid Phase Extraction
The Concept of Solid Phase Extraction
Solid Phase Extraction Cartridges (SPE column, or Solid Phase Extraction Cartridges, or SPE cartridges for short) is a sample pretreatment method based on chromatographic separation. It is a sample preparation technology developed in the mid-1980s. It is developed by a combination of liquid-solid extraction and liquid chromatography. The separation, purification, and enrichment of the sample are achieved mainly by the selective adsorption and desorption process of the sample components by the solid phase filler. Mainly used in sample pretreatment of various foods, agricultural and livestock products, environmental samples, and target compounds in biological samples.
Solid Phase Extraction Principle
Solid phase extraction (SPE) is a separation principle using liquid chromatography using selective adsorption and selective elution. The more common method is to pass a liquid sample through an adsorbent, retain the substance to be tested, and then use an appropriate strength solvent to wash away the impurities, and then elute the test substance with a small amount of good solvent. Thereby achieving the purpose of rapid separation, purification, and concentration. It is also possible to selectively adsorb the interfering impurities and let the measured substance flow out, or simultaneously adsorb the impurities and the north side substance, and then selectively elute the test substance with a suitable solvent.
The principle of solid phase extraction is based on the selective retention and subsequent elution of analytes from the solid phase. The main purpose of the solid phase extraction principle is to reduce sample matrix interference and improve detection sensitivity. SPE technology is based on liquid-solid phase chromatography theory. It uses selective adsorption and selective elution to enrich, separate, and purify samples. It is a physical extraction process that includes both solid and solid phases. It can also be approximated. Think of it as a simple chromatographic process.
Principle of solid phase extraction
The basic principle of solid phase extraction is that the liquid sample is made to pass through the adsorbent to retain the tested substance. Then the impurities are washed away with the appropriate strength solvent. Then the tested substance is eluted with a small amount of good solvent, so as to achieve the purpose of rapid separation, purification, and concentration. SPE cartridges can also selectively adsorb interfering impurities to let the tested substance flow out or adsorb both impurities and the substance to be tested, and then use the appropriate solvent to select the elution of the substance to be tested.
Since the stationary phase adsorbent has different functional groups, specific compounds can be adsorbed and retained on the SPE cartridge. This solid phase extraction principle is consistent with liquid chromatography molecules and is similarly compatible.
The solid phase extraction principle of similar compatibility means that the solute composed of polar molecules is easily soluble in the solvent composed of polar molecules due to the electrical interaction between polar molecules. A solvent dissolved in a non-polar molecule; a solute composed of a non-polar molecule is easily soluble in a solvent composed of a non-polar molecule and is insoluble in a solvent composed of a polar molecule.
Solid Phase Extraction Composition:
Solid phase extraction includes a solid phase (solid adsorbent with a certain functional group) and a liquid phase (sample and solvent). The liquid sample passes through a solid phase extraction device (solid phase extraction column, solid-phase extraction membrane, etc.) equipped with a solid adsorbent under the action of positive pressure, negative pressure, or gravity.
Advantages of solid phase extraction cartridges
Precise speed control, single flow rate 0.01~7ml/min, support large volume injection and positive pressure elution to avoid cross-contamination;
Stepless numerical control operation, LED digital display, light touch button, ergonomics mechanical design;
Corrosion-resistant roof, chassis phosphating, and multi-layer epoxy resin spraying treatment;
The chassis structure is convenient to maintain;
Multi-channel, small column joints resistant to acid, alkali, organic solvents, and oxidant corrosion;
Technical motor, using high-precision numerical control technology, low energy consumption, low noise;
The CNC pump tube adopts the American original long-life pipe.
Work modes of SPE cartridge
1. Target compound adsorption mode: When the sample passes through the SPE column, the functional group of the adsorbent acts on the target compound, the target compound remains on the SPE column, and the sample matrix is discarded.
Sample through the column (add sample and pass the solid phase extraction column)
Washing (removing impurities)
Drying (removing moisture)
Elution (elution of target compound)
2. Impurity adsorption mode: When the sample passes through the SPE column, the impurities are adsorbed by the solid phase adsorbent, and the target compound passes through the SPE column and is collected into the container. It is also used as an impurity removal mode and is commonly used in SPE columns for normal phase packing.
Silica gel matrix: Currently, the most commonly used adsorbent is still silica gel or bonded silica gel, whose pH range is 2-8. There are many kinds of silicone matrix fillers with the advantage of multiple selectivities. Non-silica gel non-polar adsorbent: varying degrees of polarity and surface alkalinity, It is mainly used for cleaning and purifying samples of the complex matrix before analysis. SPE cartridges are very popular in analytical laboratories.