The acquired ion image of glucose from the NEDC matrix seems to be the negaWve of the image that is obtained with betaine aldehyde derivaWzaWon (see figure ). This is in agreement with the results reported by Zahraei et al. . They found that ion map for glucose with RMS normalizaWon is in contradicWon with the results obtained by GC-MS analysis (so they have "negaWve image" in comparison with GC-MS results). Thus, to obtain proper image they had to use 3-O-methyl-D-glucose (3-OMG) as the internal standard and normalize to this substance. So, our method seems be]er since it is straigh}orward.