Figure 9

MALDI-ToF-MS analysis of the results of FITC labeling. (A) FITC labeling of double oxime-functionalized oligosaccharides with possible structures shown above the mass spectrum. Peak clusters representing single labeled products are a (n = 1), b (n = 2), c (n = 3) and d (n = 4), and peak clusters representing double labeled products are e (n = 1), f (n = 2), g (n = 3), and h (n = 4). This figure shows that labeling with FITC was incomplete, meaning that also singly labeled products were present. This is most likely due to the use of a short reaction time (1 h) and a low amount of FITC equivalents. (B) FITC labeling of single oxime-functionalized oligosaccharides with possible structures shown to the lower right. The signal clusters represent i (n = 0), j (n = 1), k (n = 2), l (n = 3) and m (n = 4). Note the double sodium which is typical for saccharides containing carboxylic acids^50,51. Adducts of proton, sodium and sodium salts of sodium adducts are labelled as [M+H]⁺, [M+Na]⁺ and [M+2Na−H]⁺, respectively. R corresponds to FITC or H. The spectra were generated with Flex analysis 3.4, https://www.bruker.com.