Make the switch from LLE to a synthetic solid SLE

Make the switch from liquid liquid extraction (LLE) to solid supported liquid extraction (SLE).

Liquid liquid extraction (LLE) is a common extraction technique and has been successfully used for many years.

It separates compounds that move readily or partition from the aqueous sample into the water immiscible organic extraction solvent.

As a result, the final extract of LLE can exclude salts found in a urine matrix, LLE helps to eliminate water soluble contaminants from the final extract.

Modifying the pH can also help the partitioning process encouraging compounds of interest to move into the organic phase or to help minimize matrix interferences in the final extract.

Liquid liquid extraction does have drawbacks.

Technique or technician variability, that is, different lengths or vigor of shaking can impact the reproducibility of a liquid liquid extraction method.

It can be challenging to determine where to cut between the two layers, the organic and the aqueous.

The presence of emulsions can diminish analyte recovery.

And the separation of the two solvent phases can be particularly labor intensive.

And the more samples, the more challenging it can be.

And it can be especially tedious with small sample sizes.

It's also difficult to automate, especially with large sample batches.

So how many of these problems can be fixed with solid supported liquid extraction?

The extraction method with Chem Elut S is simple.

Add your aqueous sample to the SLE cartridge, it will begin to gravity flow into the cartridge.

Allow a wait time of five minutes for complete gravity loading and equilibration.

Next, add the water immiscible extraction solvent.

Allow it to gravity flow and collect the eluent.

This solvent extraction process can be repeated.

There is no shaking and no manual solvent phase separation required.

From there, dry down, reconstitute and analyze.

There are two types of SLE media.

Diatomaceous earth (DE) is used in our standard Chem Elut brand of SLE products.

Diatomaceous earth is a mined fossil diatom, which is heterogeneous and can be inconsistent from one mine to the next.

In the new Chem Elut S, we use a synthetic SLE sorbent, which offers improved particle size distribution and offers greater batch to batch consistency.

In this workflow, we'll review a method using Chem Elut S for the extraction of drugs of abuse from urine.

For complete method details, see the application note shown.

Here we see the Chem Elut S in a 96 well plate format on Agilent's positive pressure manifold, the PPM 96.

Samples are loaded into the wells.

Small format Chem Elut S cartridges require the aqueous sample to be initially applied to the sorbent using pressure or vacuum, followed by the five minute wait time.

Larger format cartridges have the sample applied to the sorbent only by gravity.

The extraction process is then performed by using two aliquots of methyl T butyl ether.

Here we see the percent recovery comparisons for a wide range of drugs of abuse.

Shown is the new Chem Elut S in blue, a competitor's diatomaceous earth product in orange and liquid liquid extraction in red.

Shown here, Chem Elut S shows excellent reproducibility results.

In this workflow, we'll review a method using Chem Elut S for the extraction of steroids from human serum.

For complete method details, see the application note shown.

This method is similar to the prior drugs of abuse from urine method, notice however, there are three solvent extractions and the solvent is a combination of MTBE and ethyl acetate.

Once again, the Chem Elut S SLE product offers excellent recovery values.

And again, Chem Elut S shows excellent reproducibility results.

Chem Elut S delivers better recoveries and RSDs than LLE or DE SLE.

Our new 96 well plate with synthetic SLE is less tedious for small sample volumes or large number of samples.

Easily automated with a standard liquid handling robot, unlike LLE.

Ready to make the switch?