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News: Waters Oasis Sample Extraction Products

Article Date(s):07/25/2011 - 12/31/2020

Combining revolutionary sorbents with innovative hardware, Oasis® sample extraction products are the preeminent choice in solid phase extraction (SPE). Chosen for their reliable and highly selective performance, Oasis products are used by separation scientists across the globe to solve the most difficult sample preparation challenges. Researchers rely on the superior technical performance of Oasis products to achieve unmatched purity, consistency, and quality in their sample preparation methods.


  • Increased sensitivity
  • Reduced matrix effects
  • Maximum selectivity
  • Optimal recovery
  • Consistent quality

Oasis® sorbents are available in 5 different SPE chemistries, providing a range of options for method development:

Oasis HLBHydrophilic-lipophilic-balanced reversed-phase sorbent for acids, bases and neutrals

Oasis MCX: Mixed-mode cation exchange sorbent for bases

Oasis MAX: Mixed-mode anion exchange sorbent for acids

Oasis WCX: Mixed-mode weak cation exchange sorbent for strong bases and quaternary amines

Oasis WAX: Mixed-mode weak anion exchange sorbent for strong acids



The Oasis µElution plate employs a patented design that results in up to a 15x increase in concentration without requiring evaporation or reconstitution. This innovative product provides unsurpassed sensitivity and high analyte recovery.

The MS spectra for 20 pg/mL LLOQ of Doxepin and 5 pg/mL LLOQ of Angiotensin II are more than 5x the level found in the blank sample, surpassing the FDA guidelines for determining the limit of quantitation in Bioanalytical methods. A) Spiked sample, and B) Matrix blank.


Reduced Matrix Effects

In the presence of matrix interferences, the maximum sensitivity that can be achieved is limited. This constraint can be overcome using Oasis sample preparation products to clean the sample prior to further analysis.

Following extraction with an Oasis mixed-mode sorbent, the matrix effects for a panel of 5 antidepressant drugs were evaluated in multiple lots of urine. The RSDs of the matrix factors were determined to be between 5.5 and 8.4%, which are well within the 15% limit required by regulatory agencies.



Having a variety of tools for method development allows separation scientists to optimize their protocols and to achieve maximum selectivity and sensitivity. Oasis SPE products are available in a variety of sorbents and can be used in conjunction with a simple, logical approach to quickly develop new separation methods.



Variable recoveries hinder method performance and result in costly retesting that reduces laboratory productivity. Oasis products use a polymeric sorbent, which provides consistent retention and capacity—even if the sorbent dries out. The figure below shows the effect of drying on recovery for Oasis HLB versus C18 sorbents.


Oasis HLB 1cc/30 mg and C18 1cc/100 mg cartridges were conditioned on a Waters vaccuum manifold. When the methanol reached the top of the upper frit in each cartridge, vaccuum was maintained at different times to vary the cartridge drying time. The SPE protocol was then continued. The data shown are the average of three replicate extractions.


Waters detailed process design and stringent quality controls have established a new standard in batch-to-batch and lot-to-lot reproducibility for SPE sorbents. This enables scientists to develop robust, accurate, and precise analytical methods that can be seamlessly transferred to laboratories across the globe.