To check if changes in the picture are not the result of the plausible presence of various hexoses in the Wssue, we decided to perform the dried droplet analyses of 0,5 mg/ml of glucose, galactose, mannose, fructose and D-glucose 13 C6 isotope either with betaine aldehyde derivaWsaWon, or with NEDC matrix and compare them with the results from the Wssue. For all the molecules we have performed MS/MS analyses (see: figure ). Only the fructose pa]ern is different here. It should be noted that the fragmentaWon spectra form the brain and liver Wssues seem to possess addiWonal quite intensive peaks. They could come from an addiWonal substance that is co-isolated with 215 m/z peak for fragmentaWon.