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United States Department of Agriculture

Agricultural Research Service

Title: Improved Quantitative Ion Chromatography of Industrial Sugars: Removal of Interfering Amino Acids

Author
item Eggleston, Gillian

Submitted to: Journal of Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 11, 1998
Publication Date: N/A

Interpretive Summary: Amino acids were shown to interfere with the accurate quantitation of sugars in sugar industry samples, using ion chromatography an accurate measuring technique. Industrial sugar samples included beet syrup, juice and molasses samples. Sugars could be either under or over estimated, depending on the interfering amino acid. Amino acids were effectively removed by filtering samples through a cation exchange syringe filter. Removal of amino acids vastly improved sugar quantitation. The primary beneficiaries of this research is the sugar industry.

Technical Abstract: The effect of interfering amino acids on the accurate quantitation of sugars in sugar industry samples, using ion chromatography with integrated pulsed amperometric detection (IC-IPAD), was investigated. Industrial sugar samples included beet syrup, juice and molasses samples. Using sugar and amino acid standard mixtures, and industrial sugar samples, proline was found to co-elute with fructose and serine with sucrose, and both co-elutions were "additive", which caused both fructose and sucrose to be overestimated. Conversely, the co-elution of arginine with myo-inositol, and glutamine with glucose had a marked "suppressive" effect on sugar quantitation and both myo-inositol and glucose were underestimated. Various methods were investigated for their efficiency to remove interfering amino acids, but not remove sugars: prefiltering of dilute samples through cation exchange syringe filters proved the most efficient method. Using sugar and amino acid standard mixtures, within experimental error, the cation exchange filter restored the mean concentrations of myo-inositol, glucose and sucrose to expected values, and standard deviations for all sugars were reduced markedly. Removal of interfering amino acids in a beet juice from a sweet water tank caused increases in mean concentrations for myo-inositol (+4.2%) and particularly for glucose (+62.5%), and a decrease for fructose (-7.3%).

Last Modified: 9/23/2014
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