Interfacing matrix-assisted laser desorption/ionization mass spectrometry with column and planar separations

This paper presents a critical review of off-line and on-line coupling of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to liquid column separations (e.g. HPLC, GPC and CE) and planar separations (e.g. PAGE and TLC). Off-line MALDI analysis of fractions collected from HPLC, GPC and CE or spots scraped and extracted from TLC and PAGE has already become a routine practice for many laboratories. MALDI has also been used to obtain mass spectra directly from TLC plates and PAGE. The direct analysis methods range from dot-blotted samples to two-dimensional scanning of the entire gels/plates. Various combinations of on-line coupling of MALDI with column separations are also reviewed. The review discusses the strengths and limitations associated with different off-line and on-line coupling approaches.