Sample prep strategies for the clinical research lab

There is a range of strategies for the cleanup of clinical samples from simple dilute and shoot to solid-phase extraction (SPE). Solid-supported liquid extraction (SLE) and enhanced protein precipitation have seen a rise in popularity due to the techniques allowing for a higher level of cleanliness and reproducibility with minimal investment in time and labor.

In this SelectScience webinar, now available on demand, Tina Chambers, technical specialist at Agilent Technologies, explores and compares the different strategies for sample preparation in the clinical lab highlighting the versatility and reproducibility of Agilent’s Captive EMR-lipid and Chem Elute S technologies. Chambers discusses strategies that can be applied to a wide range of samples including small molecules such as pharmaceuticals, endogenous hormones, vitamins and biomarkers.

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Would the Captiva EMR or Chem Elut S technologies be appropriate for matrices such as oral fluid?

TC: The Captiva EMR is very specific for the removal of phospholipids, so it would only be appropriate for samples that contain phospholipids, which is any kind of blood product or tissue extract. Everything else, if it's a liquid, could be potentially processed on the Chem Elut S including oral fluid.

How easy is it to automate these technologies and what are the options?

TC: There are standard 96-well plates and there are 1 mL, 3 mL, and 6 mL cartridges of both the Captive EMR and Chem Elut S technologies. There are plenty of options out there for automation platforms and all these devices are compatible with these.

Do I still need to hydrolyze my urine samples if I switch to the SLE method?

TC: The hydrolysis step for some urine assays serves to cleave off the synchronized moiety that the body adds to compounds to make them more polar. In any kind of liquid extraction, the goal is to make the molecule as nonpolar as possible. These polar groups, therefore, do still need to be removed. The existing protocols for this can be kept, and they should translate into the new method.

Do I need to change methods when transferring from one SLE technology to another?

TC: That should not be necessary if your previous SLE workflow is a rugged method. One of the big advantages of solid-supported liquid extraction is that you can easily extract to exhaustion. There's a better capacity on the new synthetic material compared to the old-fashioned diatomaceous earth but the application notes that we publish use sufficient extraction solvent to isolate the analyte of interest, so there should not need to be any kind of change to the method.

I have seen some research that uses QuEChERS. Is that an option for blood samples?

TC: QuEChERS was developed specifically for the analysis of pesticide residues in fruit and vegetables. Pesticides and small molecule drugs differentiate themselves in what they do to the body or the target, but they're not vastly different from a chemistry standpoint. From that perspective, QuEChERS would work. Where QuEChERS falls apart is in the matrix removal because QuEChERS wants to remove the kind of matrix that you would encounter when you process an apple, which is water, sugar, carbohydrates. That’s a vastly different type of matrix that needs to be removed than is typically encountered in the clinical research lab. Many times, the QuEChERS methods that I see published are just very expensive dilute and shoot methods that don't accomplish much in terms of matrix removal.

For biological fluids, do you know if these technologies are suitable for speciation analysis?

TC: These techniques just take away very specific abundant matrix components such as salt and polar compounds when it comes to the Chem Elut S, or phospholipids when it comes to Captiva EMR. If whatever compound it is you're trying to speciate is not one of those, and it is compatible with the solvents used, then the technologies absolutely can be used in speciation analysis.

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