This technical note describes the extraction of basic drugs from biological fluids using non-polar ISOLUTE® SPE cartridges. The extraction of drugs from biological fluids using a purely non-polar retention mechanism can lead to extracts containing a large amount of non-polar co-extracted material, which can interfere with the subsequent analysis.
Many drugs with a generally non-polar structure also contain a basic group such as a primary or secondary amine. In order to obtain a clean extract, it is possible to utilize the ionic interactions between the exposed silanol groups of non-end capped non-polar sorbents, and the basic moiety of the drug (see Figure 1). The drug is retained by both non-polar and ionic retention mechanisms, allowing a more rigorous interference elution regime to be used. This leads to a much cleaner final extract, as many non-polar interferences which are retained by a non-polar interaction alone, can be eluted selectively, prior to elution of the drug.
As the different sorbents can have differing selectivity for analytes, we recommend that the whole range of ISOLUTE® non-polar, non-end capped sorbents be screened for each application. A list of the sorbents available along with their sorbent reference number is included in this technical note.
Literature number: TN112