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Extracting solid phase materials can be a lengthy and complicated process. In this article, we’ve put together 10 suggestions to make the process easier. These tips will help you extract the best possible outcomes, right from cleaning to drying. What are you waiting to do? Start extracting solid phase materials now!

1. New standards are the best

In the event of storage for prolonged periods of time, certain analytes are susceptible to degradation due to heat and light. They could precipitate from solution. This will impact the standard of calibration and the recovery of a procedure and any procedure should be started with freshly made standards.

2. Optimise loading pH

pH can have a huge effect on any SPE technique , and it can be employed to improve retention of chemicals on the SPE product. For instance, the reversed phase technique can be utilized to adjust pH to neutralize the charge of an analyte.

This increases the interaction with the resin and make it more hydrophobic. For the most basic compounds, you can adjust 2 pH above pKa. And for compounds that are acidic, adjust 2 pH units BELOW pKa.

3. Be aware of your compound

The properties of the compounds under study can influence the type of SPE feasible. The pKa and Log P of the compounds of importance are two of the most important numbers. pKa refers to the half-ionized points of an analyte. Log P is a measure of the hydrophobicity of a compound.

4. Composited vs. loose-packed

A loosely packed material can cause numerous problems for the sorbent bed that include channeling, compression, voiding and inconsistencies in bed weight to bed height ratio differences due to the lack of compression in the top frit following loose filling.

All of these variables could have an impact on the reliability and accuracy of test results. These issues can be eliminated by composite products like the Microlute CP range. They are specifically designed to increase the efficiency and reproducibility of SPE methods.

5. Sorbent conditioning

After the pKa of a sorbent has been determined, the sorbent can be activated and prepared to be able to bind analytes via conditioning. Silica is bound to a functional moiety which is typically present flat on the surface of the majority of silica-based SPEsorbents.

The conditioning procedure with an organic solvent that is water-miscible (e.g. MeOH), gives them the largest surface area that analytes can connect to and bind because it causes the bonded functionalities to rise up over the top.

If the sorbent isn’t water-wettable, this procedure may not be necessary. However solvent washing can increase the quality of extracts.

6. Strength of the elution and refine wash

Wash and elution strength can be altered to produce the cleanest extracts When using a mixed mode or reversed phase SPE product. Log P is the ideal property that can be used to choose these settings.

Low Log P Reduce the organic strength of the elution solvent to prevent hydrophobic interferences while still eluting an analyte of your choice.

High Log P – Use stronger organic strength during the wash step.

7. Know your sorbent

To regulate the pH of solutions in the wash and load steps, without deionizing compounds and resins (weak Ionic resins are the only ones) the pKa value of the sorbent being employed must be identified and used in conjunction with the analytes pKa.

8. Be sure to follow the flow (rates).

To achieve an efficient reversed phase SPE workflow it is essential to have flow rates. Van der Waals interactions between analytes as well as sorbents are crucial to the retention mechanism.

Immunoaffinity columns can hinder an analyte’s ability to bind properly to the sorbent media during an SPE procedure. This can lead to difficulties with the load or wash processes. Slow and steady flow is the ideal. It is recommended to achieve a flow rate of 1 drop every second (1 milliliters/minute).

9. Dry the SPE resin prior the elution

When dry, silica is very vulnerable to collapse of the stationary phase. Prior to completing the final washing step of the SPE procedure, do not let silica-based resins dry at any point which is especially important in the load phase.

Recovery can be decreased by limiting the interaction between analytes and bonded phases and other substances. These tips are applicable to silica and polymeric resins.

After the wash step(s) after which the resin should be dried using vacuum or positive pressure until resin is completely dry. Use vacuum or positive pressure for at least 3 minutes or until the solvent is gone.

Drying the resin can be an excellent way to cut down drying time, especially in the event that the process needs the reconstitution and drying of the resin. Water is present in most of the wash solvents, and it is harder than organic solvents to evaporate.

If a dry down step is not required, not drying the SPE resin immediately following the wash step can cause the final solution for injection to be less concentrated, leading to decreases in sensitivities.

10. Dry down to an optimal level

It is important to ensure that the dry down process is sufficient vigorous enough to scratch the surface of the solvent but not too vigorous so that the solution can escape out of the wells. This could result in significant recovery and %RSD variations. As the level of solvent will move when drying down, this could be quite difficult.