title: An acetate-hydroxide gradient for the quantitation of the neutral sugar and uronic acid profile of pectins by HPAEC-PAD without postcolumn pH adjustment.
abstract: An HPAEC-PAD method was developed and validated to quantitate seven neutral sugars and two uronic acids of hydrolyzed pectic polysaccharides without postcolumn pH adjustment. Due to a short gradient phase minimizing the ion concentrations after equilibrating the CarboPac PA20 column with sodium acetate and hydroxide, subsequent isocratic separation of the neutral sugars was characterized by almost baseline resolution of rhamnose and arabinose (1.45 ± 0.15) and xylose and mannose (1.21 ± 0.02) at their maximal concentrations. Linearity was shown (R² = 0.9975-0.9998) for the relevant ranges (0.28-30.3 μmol L⁻¹); galacturonic acid, 1.7-128 μmol L⁻¹) above the limits of detection (30-81 nmol L⁻¹; galacturonic acid, 179 nmol L⁻¹) and ∼3.8 times higher limits of quantification. Conformity of the findings for four pectins after methanolysis plus hydrolysis in trifluoroacetic acid with those of reference procedures (total uronic acids, 95-102%; total neutral sugars, 97-105%) proved the accuracy.
authors.affiliation: Institute of Food Science and Biotechnology, Chair of Plant Foodstuff Technology, Hohenheim University , Garbenstrasse 25, 70599 Stuttgart, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Nagel
authors.forename: Suparat
authors.initials: S
authors.lastname: Sirisakulwat
authors.forename: Reinhold
authors.initials: R
authors.lastname: Carle
authors.forename: Sybille
authors.initials: S
authors.lastname: Neidhart
mesh_terms: D002852:Chromatography, Ion Exchange / Q000295:instrumentation / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D010368:Pectins / Q000032:analysis*; D014574:Uronic Acids / Q000032:analysis*
chemical_list: D014574:Uronic Acids; D010368:Pectins