['If carbohydrates are investigated by nuclear magnetic resonance (NMR) spectroscopy, they are normally dissolved in deuterated solvents, such as D2 O. The incorporation of deuterium leads to a high complexity of subsequently recorded mass spectra and reduced sensitivity because different deuterated ions become detectable. Here, we demonstrate that the applied matrix-assisted laser desorption/ionization (MALDI) matrix solution has a considerable impact on the observed isotopic distribution.', 'Unsaturated disaccharides of chondroitin (CS) and dermatan sulfate (DS) were prepared by enzymatic digestion of the polysaccharides in D2 O and analyzed by MALDI time-of-flight mass spectrometry (TOF MS) using 2,5-dihydroxybenzoic acid (DHB) and 9-aminoacridine (9-AA) according to previously published protocols.', 'The extent of deuteration of a given compound can be easily determined by using the mass shift between the non-deuterated and deuterated ions. However, such a determination is more difficult when considering sugars due to their high content of exchangeable groups. Therefore, both the solvent and the matrix have a considerable impact on the MS patterns. Additionally, there are significant differences if the spectra are recorded at different laser fluences.'] Does the selected matrix influence the matrix-assisted laser desorption/ionization time-of-flight mass spectral patterns of partially deuterated glycosaminoglycan disaccharides?