Betaine aldehyde reacts selecWvely with hydroxyl group. This reacWon with glucose results in the formaWon of derivaWzaWon product at m/z = 282.2. We have performed MSI analysis of brain Wssue secWon with betaine aldehyde derivaWzaWon and CHCA matrix (5mg/ml ACN:H2O, 2:1; 0,2% TFA) in the posiWve ion mode and NEDC matrix (7mg/ml, 70% MeOH) in the negaWve ion mode (see: figure ). To our surprise, the ion maps obtained from these two analyses did not match to each other.