Sample Pretreatment Principle, Type and Packing Selection of SPE Cartridge

Sample Pretreatment Principle of SPE cartridge

Compared with traditional liquid-liquid extraction methods, SPE can greatly improve the recovery rate of analytes, separate analytes from interferences more effectively, and reduce sample pretreatment processes. Simple, time-saving, and labor-saving, it can be widely used in medicine, food, environment, commodity inspection, chemical industry, and other fields. SPE uses solid adsorbents to adsorb the target compound in the liquid sample, separate it from the sample matrix and interfering compounds, and then use the eluent to elute or heat to desorb the target compound to achieve the purpose of separation and abdominal muscle target compound.

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Type of SPE Cartridge

As effective experimental equipment such as sample pretreatment and condition testing, SPE cartridge have been widely used. There are many types of solid phase extraction cartridges with different specifications. The column body of the solid phase extraction column should be high purity and smooth, no dissolution when using organic solvents, no impurities on the sieve, suitable sieve pore size, and uniform pore distribution. Silica-based ionic fillers can be divided into strong cationic fillers, strong anionic fillers, weak cationic fillers, weak anionic fillers, etc. Since ionic cartridges are mostly used under alkaline conditions, and silica gel has poor alkali resistance, ionic fillers are mostly synthesized from organic matrix baseballs.

Normal Phase SPE Cartridges:

Principle: Uses a non-polar stationary phase (e.g., silica) to retain non-polar analytes while polar compounds are eluted first.
Applications: Suitable for separating non-polar or slightly polar compounds from more polar matrices.

Reverse Phase SPE Cartridges:

Principle: Employs a polar stationary phase (e.g., C18, C8) to retain polar analytes while non-polar compounds are eluted first.
Applications: Widely used for extracting and concentrating polar compounds from non-polar matrices, such as pharmaceuticals from biological fluids.

Ion-Exchange SPE Cartridges:

Principle: Utilizes charged functional groups in the stationary phase to selectively retain charged analytes based on their ionic interactions.
Applications: Ideal for separating charged analytes like amino acids, peptides, and nucleotides.

Mixed-Mode SPE Cartridges:

Principle: Combines two or more interaction mechanisms (e.g., reversed-phase and ion-exchange) in the same cartridge for enhanced selectivity.
Applications: Useful for complex samples with analytes of varying polarities.

Packing Selection of SPE Cartridge

Solid phase extraction is a process of adsorption, desorption/elution of the target substance on the stationary phase, so the factors that affect the adsorption, desorption/elution will directly affect the extraction efficiency, such as the type of filler, the strength of the elution solvent, and the pH And flow rate, etc. Packing is the core of solid-phase extraction technology. Choosing SPE cartridges packing with moderate adsorption to the target is a prerequisite to ensure accurate detection. Of course, we can choose different packings for the same target, but we must pay attention to the adjustment of the method.

Comparative advantages of SPE cartridge

Sample pretreatment is a key link in the entire analysis process. Traditional sample pretreatment techniques, such as liquid phase extraction, distillation, and filtration, are generally cumbersome and time-consuming, requiring a large number of organic solvents that are harmful to the environment and the human body and difficult to automate. Therefore, it has become a hot spot in the field of analytical chemistry to establish a new sample pretreatment technology with time-saving, high efficiency, and low consumption of organic solvents. In order to realize the automation of sample removal and minimize the use of organic solvents, Hawach’s SPE can solve the above problems.

Application Advantages of SPE Cartridge

What kind of project pretreatment is suitable to use solid phase extraction technology, that is, SPE cartridge is more ideal than ordinary solvent extraction cartridge. There are the following situations:

(1) Pretreatment of organic matter in water
This kind of conventional treatment is basically the extraction with an organic solvent that is incompatible with water. The advantage of solid phase extraction is that:

Firstly, the pre-treatment process can be repeated quantitatively. Generally speaking, the operation of solvent oscillation can only be required to control the time, but cannot control the oscillation frequency, intensity, and action. You know that everyone’s oscillation action is different, and it is difficult for the same person to guarantee a consistent action.

In the application of solid phase extraction cartridge , it is easier to maintain the uniformity and stability of the column and elution rate. Therefore, the extraction process of solid phase extraction can be repeated and quantified.

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(2) On-site treatment
The analysis of organic matter in water has a bottleneck that has plagued us for a long time. So organic matter and other samples can keep stable condition, but once it enters the small environment of the sampling bottle, it will change rapidly.

Therefore, many water organic matter analysis methods require immediate analysis, which cannot exceed 4 hours, or the reactive effect will decrease to some extent. The situation is that the time from the water collection to the laboratory is far more than 4 hours, the sample has changed, and the reliability of the analysis results can be imagined.

If the solid phase extraction technology is introduced, due to its simple equipment, small size, and ease to carry, it can be done on-site pre-processing. This will ensure that water samples that are truly stable in composition. In terms of practical application, there is still considerable work to be explored to replace traditional liquid-liquid extraction with solid-phase extraction technology in water detection. It cannot be completely replaced at present, but its development prospects are worth looking forward to.

(3) Reduction in consumption of organic reagents
When processing water samples, if solid phase extraction cartridge is used, only organic solvents need to be used for elution, and the amount is ten times more than traditional liquid-liquid extraction. It has positive significance for the personal protection and environmental protection of experimenters. Therefore, it is better to add proper amount of organic reagents according to actual needs.

Mechanism of SPE Method

The SPE method has three modes: solid phase extraction, normal phase extraction, and ion exchange extraction. The adsorbent for reverse phase extraction is non-polar or weakly polar. Its mechanism of action is non-polar-non-polar interaction van der Waals force or dispersion force. Reverse phase extraction can adsorb non-polar to medium-polar compounds from strong polar solvents. Other reverse adsorbents such as C8, similar to C18, are suitable for non-polar to moderately polar compounds, and their retention of non-polar compounds is slightly weaker than that of C18.

The adsorbent of SPE Method

The adsorbent for normal phase extraction is a polar bonded phase, and its mechanism of action lies in the polarity-polarity interaction. The interactions between the polar functional groups of polar compounds, dipole-dipole interactions, and dipole-induced dipole are interactions.

The adsorbent for normal phase extraction silica gel column is an acidic adsorbent that can adsorb acidic or neutral polar compounds. Because of the silanol group on the surface, it can release weakly acidic hydrogen ions, and it also acts as a weakly acidic cation exchanger. Adsorption of basic compounds. The ion exchange separation method relies on the interaction between the target compound and the adsorbent is electrostatic attraction.

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