Submitted to: Journal of Chromatography A
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/30/2003
Publication Date: 8/29/2003
Citation: CAMERON, R.G., HOTCHKISS, A.T., KAUFFMAN, S.W., GROHMANN, K. UTILIZATION OF AN EVAPORATIVE LIGHT SCATTERING DETECTOR FOR HIGH PERFORMANCE SIZE EXCLUSION CHROMATOGRAPHY OF GALACTURONIC ACID OLIGOMERS. JOURNAL OF CHROMATOGRAPHY A. 2003. v. 1011(1-2). p. 227-231. Interpretive Summary: Pectin is extracted from citrus fruit peel and used as a gelling agent for jams, jellies and other confectionaries. It is also used to stabilize acidic proteins present in dairy products such as yogurt. Potential industrial uses for pectin, modified pectin or pectin containing bio-based products include additives to a variety of manufactured products, ion exchange resins, flavor or aroma encapsulators and as coatings. The functional properties of pectin depend on its chemical structure. Small changes in its structural properties can produce very different functional properties. To characterize these small structural changes it is often necessary to separate and measure very small fragments of the original material. Detecting and quantifying these small fragments has been especially difficult. The techniques described in this work improve our ability to both detect and to quantify these small fragments. These techniques will allow us to reconstruct the modified structural features that resulted in new or improved functional qualities.
Technical Abstract: A high performance size exclusion chromatographic method utilizing an evaporative light scattering detector was developed to separate and quantify galacturonic acid (GA) oligomers. Values of k for GA monomer ranged from 0.16 in water to 0.67 in 100 mM acetic acid. In 40 mM acetic acid calibration curves for GA monomer, dimer and trimer were nearly identical and linear up to a concentration of 0.75% (w/v). However, this buffer precipitated polygalacturonic acid (PGA) and it could not be eluted from the column. An NH4OAc buffer at pH 3.7 also produced baseline resolution and linear calibration curves for mono-, di- and tri-GA, which could be used to estimate the concentration of tetrameric, pentameric and hexameric GA. With an NH4OAc mobile phase both pectin and PGA could be detected.