title: Polymer microchips integrating solid-phase extraction and high-performance liquid chromatography using reversed-phase polymethacrylate monoliths.
abstract: Polymer microfluidic chips employing in situ photopolymerized polymethacrylate monoliths for high-performance liquid chromatography separations of peptides is described. The integrated chip design employs a 15 cm long separation column containing a reversed-phase polymethacrylate monolith as a stationary phase, with its front end seamlessly coupled to a 5 mm long methacrylate monolith which functions as a solid-phase extraction (SPE) element for sample cleanup and enrichment, serving to increase both detection sensitivity and separation performance. In addition to sample concentration and separation, solvent splitting is also performed on-chip, allowing the use of a conventional LC pump for the generation of on-chip nanoflow solvent gradients. The integrated platform takes advantage of solvent bonding and a novel high-pressure needle interface which together enable the polymer chips to withstand internal pressures above 20 MPa (approximately 2900 psi) for efficient pressure-driven HPLC separations. Gradient reversed-phase separation of fluorescein-labeled model peptides and BSA tryptic digest are demonstrated using the microchip HPLC system. Online removal of free fluorescein and enrichment of labeled proteins are simultaneously achieved using the on-chip SPE column, resulting in a 150-fold improvement in sensitivity and a 10-fold reduction in peak width in the following microchip gradient LC separation.
authors.affiliation: Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Jikun
authors.initials: J
authors.lastname: Liu
authors.forename: Chien-Fu
authors.initials: CF
authors.lastname: Chen
authors.forename: Chia-Wen
authors.initials: CW
authors.lastname: Tsao
authors.forename: Chien-Cheng
authors.initials: CC
authors.lastname: Chang
authors.forename: Chin-Chou
authors.initials: CC
authors.lastname: Chu
authors.forename: Don L
authors.initials: DL
authors.lastname: DeVoe
mesh_terms: D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation*; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry; D007267:Injections; D046210:Microfluidic Analytical Techniques / Q000379:methods*; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D011109:Polymethacrylic Acids / Q000737:chemistry*; D011312:Pressure; D015203:Reproducibility of Results; D052616:Solid Phase Extraction / Q000295:instrumentation*; D013194:Staining and Labeling; D014357:Trypsin / Q000378:metabolism
chemical_list: D010455:Peptides; D011109:Polymethacrylic Acids; C030613:polymethacrylic acid; D014357:Trypsin; D016650:Fluorescein-5-isothiocyanate