(333p) In-Line Sample Pre-Concentration Employing Octadecylsilane

We report an in-line, solid-phase extraction based method for pre-concentrating samples using a previously reported photoinduced polymerization technique for trapping octadecylsilane (ODS) spheres in capillaries. Previous workers have used this method of particle entrapment for capillary electrochromatography and the fabrication of spray tips for capillary ESI-MS. The method allows for entrapment of ODS spheres to produce varying lengths of stationary phase without the use of retaining frits and their associated problems (bubble formation and void spaces). We entrapped a 1-2 cm length of 4 µm ODS spheres at the end of a capillary using this method and demonstrate its ability to pre-concentrate samples for detecting the oxidative DNA damage marker 8-hydroxy-2'-deoxyguanosine (8-OH-dG) using micellar electrokinetic capillary chromatography (MEKC) with UV absorption detection.