SPE Cartridge: the Essential Tool for Sample Preparation
SPE Cartridge: The Essential Tool for Sample Preparation
To isolate a species in a sample or to clean up a sample before analysis, the solid phase extraction (SPE) is called the sample preparation technique which uses a solid adsorbent to adsorb select species from the solution. The solid adsorbents are usually contained in a cartridge device, or on a disk. The goal of the solid phase extraction is to remove interferents in the matrix from the analyte and put out a solution that contains primarily the analyte.
When the sample goes through the SPE cartridge or disk very slowly, you can find that the analyte and some of the sample matrix compounds will be retained on the SPE material. The awash solvent that we have selected can remove components from the SPE sorbent and retain others at the same time, according to the properties of the analyte and the SPE sorbent.
SPE is pretty advanced in the way of simplifying complex sample matrices and purifying compounds of interest. It performs perfectly when fractionating complex mixtures for analysis by classification, and concentrating analytes present at low levels too.
(1) Instead of the traditional liquid-liquid extraction, a large amount of mutually incompatible solvents are not required; (2) No emulsification occurs during the treatment; (3) Adopting high-efficiency and highly selective adsorbent, the extraction selectivity is high and the repeatability is good; (4) Simplify the sample processing process and reduce costs.
2. Separation mode of solid phase extraction
Solid phase extraction separation mode is the same as liquid chromatography.
(1) Normal phase (adsorbent polarity is greater than eluent polarity) (2) Reversed-phase (adsorbent polarity is less than eluent polarity) (3) Ion exchange
3. Selection of elution solvent
Follow the “similar compatibility” principle and meet the following requirements.
(1) The solubility of the tested component is large; (2) The solubility to interfering impurities is small; (3) Effective release of the component to be tested; (4) The ability to dissociate proteins or fats well; (5) moderate boiling point (40 ~ 80 °C), low viscosity, low toxicity, easy to purify, low cost, and easy to further purification treatment.
According to the nature of the target compound and the type of sample, choose the appropriate SPE column and eluent.
5. Application of SPE
Separation and enrichment of trace or trace target compounds in complex samples;
For example, analysis of biological fluids (such as blood, urine, etc.), analysis of traditional Chinese medicines and their metabolites, analysis of active ingredients or harmful components in foods, and sample preparation of analysis of organic pollution in environmentally friendly water samples.
Application example: Determination of ginsenosides in healthy foods
(1) Sample processing: Weigh the appropriate amount of sample + water solution. Ultrasonic extraction for 30 min, makeup to volume, shake well, and place. (2) Chromatography column: 3 mL XAD-2 macroporous resin column (polyaromatic microspheres) + neutral alumina (100-200 mesh). (3) Column pretreatment: 25 mL of 70% ethanol, 25 mL of water. (4) Injection: Take 1 mL of sample solution into column chromatography. (5) Column washing: 25 mL of water. (6) Elution: 25 mL of 70% ethanol, collected and evaporated.
6. Good Retention for Polar Compound
Hawach scientific normal phase CN SPE cartridge is of strong retention for polar compounds in samples or compounds with similar structures. Hawach normal phase CN SPE cartridge has excellent sample load ability and wide elution volume, which makes it can be applied in different conditions such as in normal phase and reversed phase adsorbents. Moreover, it provides the strongest polarity among sorbents in the normal phase and fits for separating compounds in various samples.
7. Separation Mechanism of Normal Phase CN SPE Cartridge
Hawach Scientific normal phase CN SPE cartridge is a process in which polar substances are dissolved in non-polar solvents and adsorbed through a strongly polar stationary phase. The interaction between the two forces includes dipole pairs, hydrogen bonds, and electron pairs. Common adsorbents are alumina, magnesium silicate, diatomite, and silica gel.
Additionally, it can adsorb the target compounds in liquid samples, separate them from the matrix and interfering compounds, and then eluent them with eluent or heat desorption to achieve the purpose of separating and enriching the target compounds. Because of its safety, high recovery rate, good reproducibility, ease of operation, fast, wide application range, ease to realize automatic operation, and so on.
8. Activation of SPE Cartridge
If the cationic column of the polymer matrix is used, it can be directly sampled without activation. If the cationic column of the silica gel matrix is used, the activation is to open the carbon group chain bonded on silica gel and make it fully effective. Methanol is to dissolve with the carbon chain, and excessive water is to dissolve the sample solution.
When you perform an SPE cartridge, the first step you should do is to pre-treat the sample, such as dilution and PH adjustment. The second step is to condition the cartridge by running water or solvent through it. After that, it is time to load the sample and elute the fractions.
Solid phase extraction (SPE) is a physical extraction process that involves both liquid and solid phases. In the solid phase extraction process, the adsorption of the solid relative analyte is greater than in the liquid phase. As the sample passes through the SPE column, the analyte is adsorbed on the solid surface and the other sample components pass through the column. The analyte is then eluted with a suitable solvent to achieve separation and enrichment with the sample matrix and interfering compounds.