Determination of total nonstructural carbohydrates in tree species by high-performance anion-exchange chromatography with pulsed amperometric detection

Abstract

Tracing shifts in carbohydrate pools has become an important tool for studying the integration of plant responses to natural and anthropogenic stresses on tree species. As a result, the need for a rapid and sensitive analytical technique to measure the components in the total nonstructural carbohydrate pool in various plant tissues has increased. In this paper we report carbohydrate data for five species that were obtained using a high-performance anion-exchange chromatography method that uses an alkaline, isocratic mobile phase (160 mM NaOH) with triple-pulsed amperometric detection. This approach has been applied to the analysis of sugar alcohols, monosaccharides, disaccharides, and other oligosaccharides in ponderosa pine (Pinusponderosa Dougl. ex Laws.), black cherry (Prunusserotina Ehrh.), and other species roots, branches, stems, and needles. The results show the range of tissue concentrations found and suggest the usefulness of the anion-exchange method for the routine quantification of the total nonstructural carbohydrate pool in trees with minimal sample preparation and cleanup. Base-line resolution of the soluble carbohydrates was accomplished in less than 13 min. The chromatographic analysis of starch as glucose was complete in less than 4 min. Electrochemical detection enabled selectivity of the carbohydrates and higher sensitivity over the conventional colorimetric assays or high-performance liquid chromatography with refractive index detection. The minimum levels of quantification were 4.5 ng for myo-inositol, 4.6 ng for sorbitol, 4.5 ng for glucose and fructose, 17.1 ng for sucrose, and 29.7 ng for raffinose.