How to Operate When the SPE Cartridge Activates the Adsorbent?

As we know, five steps required for solid phase extraction cartridge: sample preparation, activation or equilibration of the column, loading, rinsing and eluting the compound of interest. There is no uniform regulation for that the solid phase extraction cartridge should be activated, rinsed and eluted with what kind of solvent. Please refer to the national standard, pharmacopeia or proven method based on your analysis.

There are two purposes for the activation of the solid phase extraction cartridge. The first purpose is to infiltrate the packing so that the sample solution can flow through the solid phase extraction cartridge; the second aim is to clean the interference impurities and solvent residue on the SPE cartridge.

Solid-phase extraction (SPE) is usually used for the pretreatment of liquid samples, extraction of semi-volatile or non-volatile compounds, or removal of impurities in the sample that interfere with the separation analysis, and can also be used for pre-dissolution of the treatment. Solid-phase samples into solvents. SPE techniques are excellent for the extraction, concentration, and purification of analytes.

1. Select the SPE Cartridge:

  • Choose an SPE cartridge that is suitable for your sample matrix and the type of analytes you are targeting. Ensure that the cartridge has the appropriate adsorbent for your application (e.g., silica, C18, ion-exchange).

2. Condition the Cartridge:

  • Prior to use, the SPE cartridge needs to be conditioned to ensure that the adsorbent is ready for efficient adsorption and elution. The conditioning process typically involves the following steps:
    • Solvent Wetting: Pass a solvent (e.g., the mobile phase or an appropriate conditioning solvent) through the cartridge to wet the adsorbent. This helps remove any air and prepares the adsorbent for proper interaction with the sample.
    • Equilibration: Condition the cartridge with the intended mobile phase or solvent to achieve a stable baseline and ensure consistent performance during the extraction process.

3. Activate the Adsorbent:

  • Activating the adsorbent is crucial for maximizing its adsorption capacity. This step enhances the affinity of the adsorbent for the target analytes. The activation process may involve the following:
    • Solvent Selection: Choose a solvent that promotes activation. Commonly used solvents include methanol, acetonitrile, or a combination of both.
    • Volume and Flow Rate: Pass a sufficient volume of the activating solvent through the cartridge at an appropriate flow rate. The volume will depend on the cartridge size and the type of adsorbent used. The flow rate should be controlled to allow proper interaction between the solvent and adsorbent.
    • Repeat if Necessary: In some cases, multiple cycles of activation may be required to ensure thorough conditioning. This is especially true for cartridges with larger bed volumes or specific adsorbents that benefit from extended activation.

4. Dry (Optional):

  • Depending on the sample matrix and the nature of the analytes, you may choose to dry the activated adsorbent. Drying can be achieved by applying a gentle stream of nitrogen or air through the cartridge. This step is particularly relevant if residual water could interfere with the extraction process.

5. Load the Sample:

  • Once the adsorbent is activated and the cartridge is conditioned, load the sample onto the cartridge. The sample should pass through the conditioned adsorbent, allowing the target analytes to adsorb onto the solid phase.

6. Wash the Cartridge:

  • After loading the sample, perform a washing step to remove unwanted matrix components and further purify the analytes. Use an appropriate wash solvent that selectively removes interfering substances while retaining the target analytes on the adsorbent.

7. Elute the Analytes:

  • Elution is the final step where the retained analytes are removed from the adsorbent. Choose an elution solvent that is compatible with your analysis technique (e.g., chromatography). The elution solvent should selectively recover the target analytes from the adsorbent.

8. Concentration and Analysis:

  • If necessary, concentrate the eluate using techniques such as evaporation or nitrogen blowdown. Analyze the concentrated eluate using the desired analytical method.

9. Dispose of the Cartridge:

  • After completing the extraction, dispose of the SPE cartridge according to your laboratory’s waste disposal procedures.

Tips and Considerations:

  • Always follow the manufacturer’s recommendations and guidelines for conditioning and activating the specific SPE cartridge you are using.
  • Monitor flow rates during the activation process to ensure proper contact between the solvent and the adsorbent.
  • Consider the compatibility of solvents with both the adsorbent and the target analytes.
  • If using multiple cartridges in a series, ensure that each cartridge is properly conditioned before sample loading.
  • Document the details of the activation process for reproducibility.

The activation of the adsorbent is a critical step in achieving reliable and reproducible results in solid-phase extraction. The specific conditions and solvents used for activation may vary based on the type of adsorbent and the nature of the analytes and sample matrix. Always refer to the product documentation provided by the SPE cartridge manufacturer for detailed instructions.

The solid-phase extraction cartridge is rinsed with a suitable solvent prior to sample extraction to keep the adsorbent moist and to adsorb the target compound or interfere with the compound. Different modes of SPE cartridge activation are different from solvents.

1. Reverse phase SPE
A weakly polar or non-polar adsorbent for reversed-phase solid-phase extraction is usually rinsed with a water-soluble organic solvent such as methanol and then rinsed with water or a buffer solution. It can also be rinsed with a strong solvent (such as hexane) prior to rinsing with methanol to eliminate impurities adsorbed on the adsorbent and its interference with the target compound.

SPE Cartridges C18 C18A SPE Cartridges

2. Normal phase SPE
The polar adsorbent used in the normal phase SPE is usually rinsed with the organic solvent (sample matrix) in which the target compound is located.

3. Ion exchange SPE
The adsorbent used in ion exchange SPE can be rinsed with a sample solvent when used in a sample in a non-polar organic solvent; when it is used in a sample in a polar solvent, it can be rinsed with a water-soluble organic solvent. Thereafter, it is rinsed with an aqueous solution of an appropriate pH and an organic solvent and a salt.

The choice of SPE cartridges
The cartridges play an important role and there are many types of SPE cartridges. Choosing a suitable one will be the first task. In the specific experimental work, it is necessary to select a suitable packing according to the analysis object, detection means and laboratory conditions, and an SPE cartridge of suitable specifications. More importantly, we should consider the extraction capacity of the SPE cartridge for the analyte, the volume of the sample solution, the final volume of the solution after elution, and the total amount of analyte and interference in the sample solution. Generally, the total mass of the analyte and the interferent adsorbed by the adsorbent in the cartridge should not exceed 5% of the total mass of the adsorbate. The volume of the eluent is typically 2.5 times the volume of the bed of the extraction cartridge.

In order to keep the adsorbent in the SPE cartridge moist until it is added to the sample after activation, approximately 1ml of the solvent for the activation treatment should be maintained on the adsorbent after the activation treatment. If the above description cannot solve your problem, please feel free to call HAWACH +86-29-89284429 or send emails to info@hawach.com. We are here to help.