Analysis of Glycosaminoglycan Oligosaccharides by Combined HPTLC/MALDI-TOF MS: Reduced Silica Gel Thickness Leads to Improved Spectral Qualities and Reduced Side Reactions

Thin-layer chromatography (TLC) is a simple, fast and inexpensive separation method which can be applied to virtually all natural products including oligosaccharides. Unfortunately, however, the unequivocal identification of a TLC spot is normally difficult. Fortunately, this problem can be minimized when mass spectrometry (MS) such as matrix-assisted laser desorption and ionization time-of-flight is used to identify the TLC spots. This work is dedicated to the TLC/MS analysis of oligosaccharides derived from native chondroitin sulfate and hyaluronan. We will show that the thickness of the silica gel layer (200 versus 100 µm) has a tremendous influence on the quality of the mass spectra: a reduced silica gel thickness enhances the spectral quality and, in particular, improves the achievable signal-to-noise ratio. Additionally, unwanted formylation of the GAG oligosaccharides (which occurs due to the high moiety of formic acid in the mobile phase) can also be minimized if MS-grade HPTLC plates are used.