A　silica-based　monolithic　column　as　polar　stationary　phase　is　proposed　for　pressurized　CEC　(pCEC).　The　monolithic　silica　matrix　from　a　sol-gel　process　was　chemically　modified　by　3-aminopropyltrimethoxysilane　to　produce　a　column　for　hydrophilic　interaction　applications.　The　amino　groups　on　the　surface　of　the　polar　stationary　phase　generated　anodic　EOF　under　acidic　conditions　and　served　at　the　same　time　as　a　weak　anion-exchanger.　The　anion　solutes　such　as　nucleotides　were　separated　by　the　mixed　mode　mechanism,　which　comprised　hydrophilic　interaction,　weak　anion-exchange,　and　electrophoresis.　The　influences　of　buffer　concentration　and　organic　modifier　content　on　the　separation　of　nucleotides　by　pCEC　have　been　investigated.　In　addition,　the　monolithic　silica　columns　were　also　able　to　separate　various　polar　compounds　such　as　phenols,　nucleic　acid　bases,　and　nucleosides　in　the　hydrophilic　interaction　CIEC　mode.　©　2006　Wiley-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim.