Immobilized antibody on a hybrid organic–inorganic monolith: Capillary immunoextraction coupled on-line to nanoLC-UV for the analysis of microcystin-LR Original Research Article

A complete characterization of a highly selective miniaturized immunosorbent (mIS) coupled on-line to nanoLC-UV is presented. A hybrid organic–inorganic monolith was synthesized in a 100 μm i.d. capillary via a sol–gel process using tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES) as precursors. After an activation step, monoclonal antibodies specific for microcystin-LR (MC-LR), the model molecule, were grafted on this porous media. The resulting mIS was coupled on-line to nanoLC-UV. Specific retention of MC-LR on the mIS was demonstrated with extraction recovery above 70% in pure water. Synthesis and grafting were repeated leading to reproducible extraction yields. The capacity of one of the prepared sorbents was determined as being 375 pg. This miniaturized device was then applied to the selective extraction of MC-LR from blue-green algae extracts and revealed to be effective in isolating MC-LR from these complex samples thus improving the reliability of its analysis at the trace level.