Salomonsen Tina, Jensen Henrik Max, Larsen Flemming Hofmann, Steuernagel Stefan, Engelsen Søren Balling
University of Copenhagen, Department of Food Science, Quality & Technology, Frederiksberg C, Denmark.
Carbohydr Res. 2009 Oct 12;344(15):2014-22. doi: 10.1016/j.carres.2009.06.025. Epub 2009 Jun 25.
Multivariate curve resolution (MCR) was applied to (13)C cross-polarisation (CP) magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra of non-depolymerised alginate powders obtained from brown seaweed plus a pure mannuronate sample isolated from Pseudomonas fluorescens for estimation of the mannuronic acid/guluronic acid ratio (M/G ratio). An excellent MCR model with a correlation coefficient of r(2)=0.99 was established between the estimated M/G ratios and the M/G ratios obtained from the traditional (1)H solution state NMR method. The new method allows for successful determination of the M/G ratio independent of the calcium content (at least up to 2.4%, which was the upper limit in this study) with a root mean square error of prediction of 0.05. It is thus concluded that (13)C CP-MAS NMR in combination with multivariate curve resolution is a reliable, convenient (no sample preparation is required) and relatively rapid method for M/G ratio determinations of alginates and it may serve as a good alternative to the chemical techniques traditionally used.
多变量曲线分辨（MCR）应用于从褐藻获得的未解聚藻酸盐粉末以及从荧光假单胞菌分离得到的纯甘露糖醛酸样品的碳-13（¹³C）交叉极化（CP）魔角旋转（MAS）核磁共振（NMR）光谱，以估算甘露糖醛酸/古洛糖醛酸比率（M/G比率）。在估算的M/G比率与通过传统的氢-1（¹H）溶液态NMR方法获得的M/G比率之间建立了相关系数r² = 0.99的出色MCR模型。该新方法能够成功测定M/G比率，且与钙含量无关（至少高达2.4%，这是本研究中的上限），预测均方根误差为0.05。因此得出结论，¹³C CP-MAS NMR结合多变量曲线分辨是一种可靠、便捷（无需样品制备）且相对快速的测定藻酸盐M/G比率的方法，它可作为传统化学技术的良好替代方法。
