Negative-ion MALDI mass spectra of Arixtra, sodium salt, obtained with DHBB/methanol matrix (panel A) and ImCHCA/methanol matrix (panel B). Fragments due to the sulfate loss are denoted [Fn]−, where [Fn]− = [M − Na − nSO3Na + nH]−. Positive-ion MALDI mass spectra of SOS, sodium salt obtained with DHBB/methanol matrix (panel C) and ImCHCA/methanol matrix (panel D). Fragments due to the sulfate loss are denoted [Fn]+, where [Fn]+ = [M + Na − nSO3Na + nH]+. Peak due to the matrix is marked with triangle.