Role of Barium Ions in the Anion-Exchange Chromatographic Separation of Carbohydrates with Pulsed Amperometric Detection

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• 作者：Tommaso R. I. Cataldi ; Cristiana Campa ; Giovanna Margiotta ; and Sabino A. Bufo
• 刊名：Analytical Chemistry
• 出版年：1998
• 出版时间：September 15, 1998
• 年：1998
• 卷：70
• 期：18
• 页码：3940 - 3945
• 全文大小：113K
• 年卷期：v.70,no.18(September 15, 1998)
• ISSN：1520-6882

文摘

Barium ion is shown here as an effective component ofalkaline mobile phases for improving the separation ofcarbohydrates in anion-exchange chromatography withpulsed amperometric detection. We demonstrate that theintroduction of barium ensures a complete removal ofcarbonate, making it possible to carry out a large numberof separations without column reequilibration after eachrun. This is particularly helpful when diluted alkalineeluents (i.e., <20 mM NaOH) are employed. Under suchexperimental conditions, the analysis time of carbohydrates is drastically reduced and the reproducibility of thechromatographic data greatly improved. For example, thenormalized capacity factor (k'/k'₀) of lactulose, whichrepresents the most retained compound investigatedusing 16 mM NaOH as the eluent, exhibits only a slightdecrease from 1.00 to 0.94 after 7.5 h of chromatographic run. The net improvement in the peak shape ofD-ribose, D-allose, and D-talose has been interpreted byconsidering the complex formation between barium andsugar molecules having an axial-equatorial-axial sequence of three OH groups on the six-membered ring. Thepresence of Ba(II) (0.5-0.7 mM) in alkaline eluents hasbeen demonstrated by ion chromatography with conductivity detection.