This application note describes a liquid separation method using Agilent Bond Elut Plexa PCX for mixed mode ion exchange to fractionate acidic, neutral, and basic drugs from plasma. The method uses mixed mode polymer ion exchange technology to retain neutral and acidic compounds from biofluids via hydrophobic interactions and concentrates basic compounds by interacting with the sorbent’s cation exchange properties.
The document details the use of the Agilent Bond Elut Plexa PCX mixed-mode polymeric solid phase extraction (SPE) sorbent for extracting multiple drug classes from biofluids. The method leverages hydrophobic interactions to retain acidic and neutral compounds while utilizing cation exchange properties to concentrate basic analytes.
The procedure requires diluting 100 yL of human plasma with a specific acid solution.
Elution of basic drugs uses 500 pL of a mixture containing 5% ammonia, methanol, and acetonitrile.
The combined solid phase extraction and LC/MS/MS analysis achieves a limit of detection of 1.0 ng/mL.