PROCEDURE INVOLVING TWO PHASES
The analytes are extracted from the matrix by the use of acetonitrile and different types of salts and buffers. After the partition liquid-liquid (LLE) it follows: shaking, centrifugation and collection of acetonitrile phase.
Deriving from the first step, the organic phase (acetonitrile extract) comes in contact with other typical clean up sorbents: primary and secondary amine (PSA), graphitized carbon black (GCB) or C18 with the purpose of removing sugars, lipids, sterols, organic acids, proteins, carotenoids, chlorophyll and other pigments in addition to the residual water by the use of magnesium sulfate. After that it follows shaking and centrifugation. The anhydrous acetonitrile phase is ready for analysis in GCMS / MS directly (LVI) or after exchange of solvent, while the injection LCMS / MS is ready after sample dilution with mobile phase.