Insights into the capillary electrophoresis separation of heparin disaccharides from nuclear magnetic resonance, pKa, and electrophoretic mobility measurements.

Determination of the pK(a) values of heparin disaccharide functional groups can provide insights into the nature of glycosaminoglycan (GAG)-protein interactions and prove useful for optimization of the charged-based separations typically used in GAG analysis. In order to gain a better understanding into the capillary electrophoresis (CE) separation process, the pK(a) values of the carboxylate and primary amine moieties of 11 heparin disaccharide standards were determined through (1)H NMR detected pH titrations. These pK(a) values were used to calculate the effective net charge of each disaccharide and compared to the electrophoretic mobilities measured by CE.

Heterogeneity of depolymerized heparin SEC fractions: to pool or not to pool?

In the structural analysis of heparin and heparan sulfate, it is customary to combine or pool like-sized fractions obtained by size-exclusion chromatography (SEC) of enzymatically derived heparin oligosaccharides. In this study, we examine the heterogeneity of preparative-scale SEC fractions obtained from enzymatic digests of porcine intestinal mucosa heparin. Each fraction was profiled by capillary electrophoresis with UV detection (CE-UV) using a 60 mM formic acid running buffer at pH 3.

Separation and analysis of trace degradants in a pharmaceutical formulation using on-line capillary isotachophoresis-NMR.

NMR spectroscopy is widely used in the pharmaceutical industry for the structure elucidation of pharmaceutical impurities, especially when coupled to a separation method, such as HPLC. However, NMR has relatively poor sensitivity compared with other techniques such as mass spectrometry, limiting its applicability in impurity analyses. This limitation is addressed here through the on-line coupling of microcoil NMR with capillary isotachophoresis (cITP), a separation method that can concentrate dilute components by 2-3 orders of magnitude.