Challenges in analysis of high-molar mass dextrans: Comparison of HPSEC, AsFlFFF and DOSY NMR spectroscopy

• Published in: Carbohydrate polymers 2014, Vol.99, p.199-207
• Main Authors: Maina, Ndegwa Henry, Pitkänen, Leena, Heikkinen, Sami, Tuomainen, Päivi, Virkki, Liisa, Tenkanen, Maija
• Format: Article
• Language: English
• Subjects: Applied sciences; AsFlFFF; Biological and medical sciences; Calibration; Chemical Fractionation; Chromatography, Gel; Dextran; Dextrans - chemistry; Dextrans - isolation & purification; Dimethyl Sulfoxide - chemistry; DOSY; Exact sciences and technology; Food engineering; Food industries; Fundamental and applied biological sciences. Psychology; General aspects; HPSEC; Leuconostoc - chemistry; Leuconostoc citreum; Magnetic Resonance Spectroscopy - methods; Molecular Weight; Natural polymers; Physicochemistry of polymers; Polysaccharides; Reference Standards; Solutions; Solvents - chemistry; Starch and polysaccharides; Water - chemistry; Weissella - chemistry; Weissella confusa
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2013.08.021

•HPSEC, AsFlFFF and DOSY NMR spectroscopy analysis of dextrans.•Dimethyl sulfoxide solutions provided the molar mass of individual dextran chains.•With increasing molar mass, aqueous solutions consisted of individual dextran chains and aggregates.•The molar mass and hydrodynamic properties of Weissella confusa VTT E-90392 and Leuconostoc citreum VTT E-93497 dextrans reported. Dilute solutions of various dextran standards, a high-molar mass (HMM) commercial dextran from Leuconostoc spp., and HMM dextrans isolated from Weissella confusa and Leuconostoc citreum were analyzed with high-performance size-exclusion chromatography (HPSEC), asymmetric flow field-flow fractionation (AsFlFFF), and diffusion-ordered NMR spectroscopy (DOSY). HPSEC analyses were performed in aqueous and dimethyl sulfoxide (DMSO) solutions, while only aqueous solutions were utilized in AsFlFFF and DOSY. The study showed that all methods were applicable to dextran analysis, but differences between the aqueous and DMSO-based solutions were obtained for HMM samples. These differences were attributed to the presence of aggregates in aqueous solution that were less prevalent in DMSO. The study showed that DOSY provides an estimate of the size of HMM dextrans, though calibration standards may be required for each experimental set-up. To our knowledge, this is the first study utilizing these three methods in analyzing HMM dextrans.