ABSTRACT
Strategies .............................................................. 449 11.2.4 Direct vs. Indirect Fluorescence Detection ......................... 452 11.2.5 Applications ......................................................................... 452
11.2.5.1 DNA ..................................................................... 453 11.2.5.2 Protein, Peptides, and Amino Acids.................... 453
11.2.6 Other Optical Detection Methods ....................................... 455 11.2.6.1 Absorbance Detection .......................................... 455 11.2.6.2 Chemiluminescence ............................................. 459 11.2.6.3 Shah Convolution Fourier Transform.................. 461 11.2.6.4 Refractive Index................................................... 462 11.2.6.5 Raman Spectra ..................................................... 462 11.2.6.6 Near-IR Spectra.................................................... 463
11.2.7 Future Directions ................................................................. 463 11.3 Mass Spectrometric Detection.......................................................... 463
11.3.1 Introduction.......................................................................... 463 11.3.2 Ionization Methods .............................................................. 464
11.3.2.1 Electrospray Ionization ........................................ 464 11.3.2.2 Matrix-Assisted Laser Desorption Ionization...... 465
11.3.3 Mass Analyzers.................................................................... 465 11.3.3.1 Quadrupole Mass Spectrometer........................... 466 11.3.3.2 Time-of-Flight Mass Analyzer ............................ 467 11.3.3.3 Tandem Mass Spectrometry ................................ 467
11.3.4 Microchip Substrates for CE-MS ....................................... 468 11.3.5 Interfacing Microchip CE to MS......................................... 469
11.3.5.1 Microchip CE-Electrospray Ionization................ 469 11.3.5.2 Microchip CE-MALDI ........................................ 470
11.3.6 Applications ......................................................................... 472 11.3.7 Future Directions ................................................................. 473
11.4 Electrochemical Detection................................................................ 474 11.4.1 Introduction to Electrochemical Detection ......................... 474 11.4.2 Amperometric Detection ..................................................... 474
11.4.2.1 Introduction to Amperometric Detection ............ 474 11.4.2.2 Instrumental Design ............................................. 475 11.4.2.3 Applications ......................................................... 481
11.4.3 Conductivity Detection........................................................ 482 11.4.3.1 Introduction .......................................................... 482 11.4.3.2 Instrumental Design and Considerations ............. 483 11.4.3.3 Applications ......................................................... 487
11.4.4 Potentiometric Detection ..................................................... 488 11.4.5 Future Direction of Electrochemical Detection .................. 489
11.5 Conclusions....................................................................................... 489 Acknowledgments ....................................................................................... 489 References.................................................................................................... 490
Detecting discrete separation bands that have been produced by microchip-
based separation techniques is a challenging task. Most of the initial studies
involving microchip CE focused on the fabrication, injection, and separation
in
aspects, with detection being accomplished by laser-induced fluorescence
(LIF).1-4 More recently, researchers have realized the importance of other
methods of detection for microchip CE and the challenges associated with
them.5,6 In addition, it has become evident that to increase the applicability
and versatility of these systems, detectors other than LIF need to be explored.
