Another material under investigation for preparing plasma samples is diatomaceous earth or diatomite-like substrate. The porous and channel structures of diatomite offer excellent dispersive properties to trap large molecules such as phospholipids. When a plasma sample passes this specially treated diatomite material, it will spread and penetrate into the pores, to form an aqueous film on the surface of the packing. When a water-immiscible liquid is passing through the diatomite, LLE occurs on the solid support. The procedure is called supported liquid extraction (SLE). Thus, analytes will be extracted while lipids are retained. It is believed that the acidic property of the hydroxyl groups and metal centers on the substrate contribute to the retention of phospholipids via the interaction with its choline and phosphate groups.

Using MAS or SLE to prepare plasma samples simplifies operation procedure. Unlike SPE, a single organic solvent is used for either MAS or SLE clean-up. A polar solvent such as ACN is used for MAS and a nonpolar solvent such as methyl tert-butyl ether is used for SLE. After the clean-up procedure, a generic concentration step is followed. The simplicity of MAS and SLE procedures can be easily adapted to high-throughput formats, such as multiple-well microtiter plates or sample arrays.

The MAS and SLE technologies provide new solutions to meet the challenges of sample preparation in the drug metabolism and pharmacokinetic (DMPK) studies. The development of MAS and SLE new materials is hardly comparable to the discovery of new drugs, but we hope these techniques will be great vehicles in establishing methods that will be characterized by simple, fast, efficient and high-throughput sample preparation, for the drug discovery environment.

Steps using MAS-C for plasma sample clean-up

Steps using MAS-C for plasma sample clean-up
  1. Activate the MAS-C column with acetonitrile
  2. Add the plasma sample into the MAS-C column
  3. Add eluent and wait for 3-4 min for precipitation
  4. Apply vacuum to get the solution through the column and collect the pass-through solution

Add more solution for elution, collect and combine all eluent, followed by evaporate solvents and reconstitute the sample with mobile phase for HPLC or LC-MS analysis.

Features and advantages using MAS columns for serum sample preparation

  • MAS use only to adsorb impurities, but in conventional SPE method, interference matrices are adsorbed and eluted with target compounds
  • MAS employ the sorbent modified with different functional groups that could, simultaneously remove variety of impurities in one step
  • MAS has good separation ability and selectivity for the proteins, peptides, amino acids, phospholipids and more biological interference matrix.
  • By choosing suitable conditions (solvent and pH), most of the biological interference can be removed, and to ensure strong water-soluble substances tested with more than 70% recovery rate, also for further separation and LC-MS detection.

More about the MAS technologies

The most convenient and general approach for plasma sample clean-up: multifunction adsorption and supported liquid extraction Bioanalysis, February 2012, Vol. 4, No. 3, Pages 223-225, DOI 10.4155/bio.11.332 (doi:10.4155/bio.11.332)

More applications using MAS

Information about the MAS products

Check more here