Recovery Rate, Extraction Speed, and Sample Capacity of SPE Cartridge

As we know, the quality of the packing in the SPE cartridge affects its adsorption capacity. The adsorption capacity refers to the total mass of compounds (including target compounds and some interfering substances) that a certain mass of adsorbent can retain under certain conditions.

1. Recovery Rate:

  • The recovery rate in SPE refers to the percentage of the target analyte that is successfully extracted from the sample matrix. Several factors can affect the recovery rate:
    • Chemical Compatibility: Ensure that the sorbent material in the SPE cartridge is chemically compatible with the analyte of interest.
    • Sample Matrix Interference: Matrix components in the sample can interfere with analyte recovery. Optimizing the method to minimize interference is crucial.
    • Elution Solvent: The choice of elution solvent and its strength can impact the recovery. Use an elution solvent that efficiently desorbs the analyte from the sorbent.

2. Extraction Speed:

  • Extraction speed refers to the time required to complete the extraction process. Factors influencing extraction speed include:
    • Particle Size of Sorbent: Smaller particle sizes provide a larger surface area for interaction with the sample, potentially increasing extraction speed.
    • Flow Rate: The rate at which the sample or solvent is passed through the cartridge affects extraction speed. Optimize flow rates for efficient extraction without compromising recovery.

3. Sample Capacity:

  • Sample capacity is the maximum amount of sample that the SPE cartridge can effectively process. Factors influencing sample capacity include:
    • Sorbent Mass: The amount of sorbent material in the cartridge determines its capacity. Higher sorbent mass generally allows for the processing of larger sample volumes.
    • Sample Volume: The volume of the sample being processed affects the sample capacity. Ensure that the sample volume falls within the recommended range for the specific cartridge.

Tips for Optimization:

  1. Conditioning and Equilibration:
    • Properly condition and equilibrate the SPE cartridge before sample loading. This ensures consistent performance and enhances recovery.
  2. Optimized Solvent Volumes:
    • Use optimized volumes of solvents for conditioning, sample loading, washing, and elution. Excessive volumes may dilute the analyte, while insufficient volumes may compromise extraction efficiency.
  3. Elution Fractionation:
    • Consider fractionating the elution solvent to collect multiple fractions. This can help in concentrating the analyte and improving overall recovery.
  4. Matrix-Matched Standards:
    • Use matrix-matched standards to account for matrix effects and enhance accuracy in quantification.
  5. Quality Control:
    • Implement quality control measures, including the use of internal standards and regular performance checks, to ensure reliable and reproducible results.
  6. Sorbent Selection:
    • Choose the appropriate sorbent material based on the analyte properties and sample matrix. Different sorbents exhibit varying selectivities.

Always refer to the manufacturer’s guidelines and recommendations for the specific SPE cartridge being used. Optimizing these parameters will help achieve the best balance between recovery rate, extraction speed, and sample capacity for your particular application.

Common specifications of adsorption capacity

Silica gel matrix: the cartridge capacity does not exceed 5% of the mass of the SPE packing material. For example, a 100 mg/1 ml C18 cartridge can retain 5 mg of the compound.
Polymer matrix: The cartridge capacity is 3 times that of the silica-based adsorbent. For example, a 100 mg/1ml BRP cartridge can retain 15 mg of the compound.
Ion exchange adsorbent: the exchange capacity is 0.25-1mmol/g, 1mmol/g means that 1g adsorbent can adsorb 1mmol of monovalent charged substances.

Therefore, in solid-phase extraction, it is very important to select the appropriate cartridge specifications according to the sample load. When the sample load exceeds the adsorption capacity of the adsorbent packing, the target compound will no longer be retained by the adsorbent but will flow out of the SPE cartridge with the sample matrix, resulting in a decrease in the recovery rate.

SPE Cartridges

Balancing The Extraction Speed And Sample Capacity

Solid phase extraction (SPE) is a rapid, effective, economical path to remove interfering compounds and concentrate or extract the analyte in a preferred solvent.

On one hand, SPE and chromatography are based on the same principles: SPE uses the HPLC column solid phase packing with materials in a single-use container, and the scientists can choose different stationary phases just like HPLC columns; but on the other hand, SPE is different from HPLC, performing as a low resolution and very low-pressure method which is designed for samples preparation by removing interfering substances or concentrating a sample.

SPE cartridge, which are single-use plastic tubes Is the key part of the SPE technique. Before you choose the SPE cartridge, there is something you should know. First, the cartridge volume should match the wash solvent volume including the volume of the sample and solvent added. The sample can be loaded in 5-10% of the sorbent weight in a given SPE cartridge.

If you choose the smaller cartridge, which contains smaller amounts of sorbent and requires less solvent for elution as well, the separation will be more efficient. When you need larger volumes of solvent, you also need the SPE cartridge in larger sizes. A larger sorbent amount will be helpful if the analytes are difficult to retain on a cartridge. So when you choose the SPE cartridge, it’s important to balance the extraction speed and sample capacity.

As a popular sample preparation technique, SPE can help to prevent problems when we practice liquid/liquid extraction, such as incomplete phase separations, and less-than-quantitative recoveries. It can avoid using expensive, breakable specialty glassware, and cut down the disposal of organic solvents as well.

Being more efficient than liquid/liquid extraction, SPE yields quantitative extractions that are easy to perform. The SPE is advanced in sample extraction, concentration, and cleanup. It is important to select the most suitable product for each application and sample. Hawach is always available with SPE cartridges in a variety of chemistries and adsorbents and different sizes for you.