chapter  8
24 Pages

Microfabricated Devices for Smaple Ectraction, Concentrations, and Related Sample Processing Technologies

CONTENTS 8.1 Introduction ................................................................................................ 214 8.2 Sample Extraction and Concentrations.................................................. 214

8.2.1 Solid-Phase Extraction Techniques on Microchips.................. 215 8.2.2 Field Amplification Stacking Techniques on Microchips ....... 218 8.2.3 Field-Amplified Injection on Microchips .................................. 218 8.2.4 Stacking of Neutral Analytes ...................................................... 219 8.2.5 Isotachophoresis for Sample Preconcentration ........................ 219

8.3 Derivatization of Samples ........................................................................ 220 8.3.1 Labeling and Complexation on Microchips ............................. 220 8.3.2 Postcolumn Reactors for Derivatization ................................... 221 8.3.3 Precolumn Reactor Derivatization ............................................. 222 8.3.4 Postcolumn Reactors for Chemiluminescence

on Microchips ................................................................................ 223 8.3.5 Miniaturized Flow Injection Analysis (µFIA)........................... 224

8.4 Microfabricated Dialysis Devices............................................................ 224 8.4.1 Microfabricated Single-Stage Microdialysis Device

for Fast Desalting of Biological Samples................................... 224 8.4.2 Microfabrcated Dual-Stage Microdialysis Device

for Rapid Fractionation and Cleanup of Complex Biological Samples ........................................................................ 227

8.4.3 Application to Complex Cellular Samples ............................... 230 8.5 Conclusions................................................................................................. 232 Acknowledgments .............................................................................................. 232 References ............................................................................................. 233

During the past decade, microfluidic analytical systems fabricated on silica, glass, and polymer microchips have undergone explosive growth. Much attention has been paid to capillary electrophoresis (CE) microchips owing to their high degree of integration, portability, minimal solvent and reagent consumption, high performance, and speed [1-3]. These microchip analysis systems hold considerable promise for applications such as environmental monitoring, biomedical and pharmaceutical analysis, clinical diagnostics, and forensic investigations. Many microfluidic systems were produced on glass substrates using standard photolithographic techniques [3-5], whereas some polymer chips were fabricated based on techniques such as in situ polymerization [6], laser ablation [7], imprinting [8], and injection molding [9].