Off-Line Coupling of High-Resolution Capillary Electrophoresis to MALDI-TOF and TOF/TOF MS

• Published in: Journal of proteome research 2002-03, Vol.1 (2), p.171-179
• Main Authors: Rejtar, Tomas, Hu, Ping, Juhasz, Peter, Campbell, Jennifer M, Vestal, Marvin L, Preisler, Jan, Karger, Barry L
• Format: Article
• Language: English
• Subjects: Electrophoresis, Capillary; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
• ISSN: 1535-3893; 1535-3907
• DOI: 10.1021/pr015519o

High-resolution capillary electrophoresis has been coupled to MALDI-TOF and TOF/TOF MS through off-line vacuum deposition onto standard stainless steel MALDI targets. This off-line approach allowed the decoupling of the separation from the MS analysis, thus allowing each to be independently optimized in terms of time. Using BSA tryptic digest as a model sample, the deposited streaks, roughly 100-μm wide, were first analyzed in the MS mode, consuming only a fraction of the sample. After data analysis, segments of the deposited trace, containing unidentified peptides, as well as several species chosen for sequence confirmation, were reanalyzed in the MS/MS mode using MALDI-TOF/TOF MS. Additionally, it is shown that the shot-to-shot reproducibility of the vacuum-deposited trace (5% RSD) is 1 order of magnitude lower than that found for the standard dried droplet method. Moreover, a linear dependence of signal intensities (relative to an internal standard) over 3 orders of magnitude was found for a peptide sample with concentrations ranging from 1 to 1000 nM. This paper demonstrates the potential of off-line coupling of high-resolution separations to MALDI-MS and MALDI-MS/MS using vacuum deposition for the analysis of complex peptide mixtures from protein digests. Keywords: high-resolution separation • capillary electrophoresis • MALDI-TOF MS • MALDI-TOF/TOF MS