A variety of carbohydrates, in particular polysaccharides can be subjected to chemical modification to obtain derivatives with amphiphilic properties, which enable biochemical or biological reactions at the polymer surface. In the present work, a polydisperse maltodextrin mixture of average molecular weight 3000 was coupled with 1,6-hexamethylenediamine (HMD) via reductive amination reaction. Resulting products were characterized by thermal analysis and positive nanoelectrospray quadrupole time-of-flight (Q-TOF) mass spectrometry (MS) and tandem mass spectrometry (MS/MS). Both thermal analysis and MS screening confirmed the formation of the HMD-polysaccharide coupling products. Moreover, HMD-linked polysaccharide chains containing 2 to 26 glucose building blocks were identified by nanoESI Q-TOF MS. MS/MS fragmentation using collision-induced dissociation (CID) at low ion acceleration energies provided strong evidence for HMD-maltodextrin linkage formation and the set of sequence ions diagnostic for the composition and structure of a HMD-linked chain containing 18 glucose residues.© Versita Warsaw and Springer-Verlag Berlin Heidelberg.

A novel strategy was developed to extend the application of electrospray ionization (ESI) Fourier transform ion cyclotron resonance (FTICR) mass spectrometry (MS) to the analysis of long-chain polysaccharides. High molecular weight polydisperse maltodextrins (poly-alpha(1-4) glucose) and dextrans (poly-alpha(1-6) glucose) were chosen as model compounds in the present study. Increased ionization efficiency of these mixtures in the positive ion mode was achieved upon modification of their reducing end with nitrogen-containing groups. The derivatization method is based on the formation of a new C--N bond between 1,6-hexamethylenediamine (HMD) and the reducing end of the polysaccharide, which exists in solution as an equilibrium between the hemiacetal and the open-ring aldehyde form. To achieve the chemical modification of the reducing end, two synthetic pathways were developed: (i) coupling of HMD by reductive amination and (ii) oxidation of the hemiacetal to lactone, followed by ring opening by HMD to yield the maltodextrin lactonamide of 1,6-hexanediamine (HMMD). Amino-functionalized polysaccharides were analyzed by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FTICR-MS) in the positive ion mode by direct flow injection. The hexamethylenediamine (HMD) and maltodextrin lactonamide of 1,6-hexanediamine (HMMD) moieties provide increased proton affinities which dramatically improve the detection of the long-chain polysaccharides by FTICR-MS. The present approach allowed for identification of single components in mixtures with prominent heterogeneity in the degree of polymerization (DP), without the need for chromatographic separation prior to MS. The high mass accuracy was essential for the unambiguous characterization of the species observed in the analyzed mixtures. Furthermore, molecular components containing up to 42 glucose residues were detected, representing the largest polysaccharide chains analyzed so far by ESI FTICR-MS.

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Polyphenylalkane derivativesPolyphenylalkane derivatives Q 0720 Nitrobenzophenones and Their Derivatives. Part 3. New Acetals of Mono-and Dinitrobenzophenones. -A novel method for the preparation of acetals such as (III) is presented. -(SISU*, E.; SISU, I.; DINCA, N.; CSUNDERLIK, C.; OPREAN, I.; RUSU, V.; MRACEC, M.; Rev.

In this study maltose, maltotriose and maltotetraose were for the first time, coupled to 4,4′-methylenedianiline (MDA). The aim of this preliminary work was to test the feasibility of oligo- and polysaccharide coupling to MDA and the characterization of the coupling products by high resolution mass spectrometry (MS). (+) nanoESI in combination with a quadrupole time of flight (QTOF) MS in full scan (MS) and MS/MS was optimized first on underivatized maltose, maltotriose and maltotetraose. The optimal screening and sequencing conditions were further applied to the MDA-functionalized oligosaccharides. The obtained results revealed a straightforward MS detection of the functionalized oligomers, high sequence coverage and a fragmentation pathway with the formation of B and Y ions as well as the complementary C and Z ions along with a typical cleavage of the aglycon. We consider that this methodology is fully applicable also to polydisperse mixtures of long chain polysaccharides, which due to the large number of components and their size require a systematic method of development and testing.